Add libevent to the Mac SCons build of net_unittests: * Build base/tcp_client_socket_libevent.cc on both Linux and Mac. * Link against -levent on both Linux and Mac. * Don't build base/cookie_policy_unittest.cc on Mac (yet?); it throws   warnings (and is currently not being built by XCode, either). Review URL: http://codereview.chromium.org/4257
Add libevent to the Mac SCons build of net_unittests:
* Build base/tcp_client_socket_libevent.cc on both Linux and Mac.
* Link against -levent on both Linux and Mac.
* Don't build base/cookie_policy_unittest.cc on Mac (yet?); it throws
  warnings (and is currently not being built by XCode, either).
Review URL: http://codereview.chromium.org/4257

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@2561 0039d316-1c4b-4281-b951-d872f2087c98

TheTypoMaster/chromium-crosswalk,junmin-zhu/chromium-rivertrail,rogerwang/chromium,fujunwei/chromium-crosswalk,dednal/chromium.src,jaruba/chromium.src,hgl888/chromium-crosswalk-efl,timopulkkinen/BubbleFish,robclark/chromium,markYoungH/chromium.src,hgl888/chromium-crosswalk,axinging/chromium-crosswalk,rogerwang/chromium,axinging/chromium-crosswalk,timopulkkinen/BubbleFish,zcbenz/cefode-chromium,hgl888/chromium-crosswalk-efl,fujunwei/chromium-crosswalk,krieger-od/nwjs_chromium.src,M4sse/chromium.src,crosswalk-project/chromium-crosswalk-efl,Chilledheart/chromium,mohamed--abdel-maksoud/chromium.src,littlstar/chromium.src,axinging/chromium-crosswalk,timopulkkinen/BubbleFish,Pluto-tv/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,krieger-od/nwjs_chromium.src,Pluto-tv/chromium-crosswalk,Just-D/chromium-1,patrickm/chromium.src,rogerwang/chromium,hujiajie/pa-chromium,littlstar/chromium.src,chuan9/chromium-crosswalk,timopulkkinen/BubbleFish,Pluto-tv/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,M4sse/chromium.src,ChromiumWebApps/chromium,hujiajie/pa-chromium,markYoungH/chromium.src,krieger-od/nwjs_chromium.src,crosswalk-project/chromium-crosswalk-efl,robclark/chromium,TheTypoMaster/chromium-crosswalk,hujiajie/pa-chromium,rogerwang/chromium,robclark/chromium,hgl888/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,rogerwang/chromium,fujunwei/chromium-crosswalk,Chilledheart/chromium,ltilve/chromium,Pluto-tv/chromium-crosswalk,zcbenz/cefode-chromium,ltilve/chromium,M4sse/chromium.src,Jonekee/chromium.src,mohamed--abdel-maksoud/chromium.src,ondra-novak/chromium.src,ondra-novak/chromium.src,littlstar/chromium.src,pozdnyakov/chromium-crosswalk,zcbenz/cefode-chromium,pozdnyakov/chromium-crosswalk,dednal/chromium.src,anirudhSK/chromium,timopulkkinen/BubbleFish,PeterWangIntel/chromium-crosswalk,robclark/chromium,dushu1203/chromium.src,krieger-od/nwjs_chromium.src,zcbenz/cefode-chromium,chuan9/chromium-crosswalk,M4sse/chromium.src,ChromiumWebApps/chromium,rogerwang/chromium,hgl888/chromium-crosswalk-efl,ChromiumWebApps/chromium,bright-sparks/chromium-spacewalk,M4sse/chromium.src,hgl888/chromium-crosswalk,markYoungH/chromium.src,krieger-od/nwjs_chromium.src,junmin-zhu/chromium-rivertrail,hgl888/chromium-crosswalk,littlstar/chromium.src,Chilledheart/chromium,nacl-webkit/chrome_deps,crosswalk-project/chromium-crosswalk-efl,patrickm/chromium.src,anirudhSK/chromium,Just-D/chromium-1,crosswalk-project/chromium-crosswalk-efl,ondra-novak/chromium.src,keishi/chromium,krieger-od/nwjs_chromium.src,ltilve/chromium,dednal/chromium.src,littlstar/chromium.src,keishi/chromium,keishi/chromium,mohamed--abdel-maksoud/chromium.src,markYoungH/chromium.src,jaruba/chromium.src,Fireblend/chromium-crosswalk,junmin-zhu/chromium-rivertrail,axinging/chromium-crosswalk,M4sse/chromium.src,nacl-webkit/chrome_deps,zcbenz/cefode-chromium,Jonekee/chromium.src,keishi/chromium,pozdnyakov/chromium-crosswalk,Fireblend/chromium-crosswalk,zcbenz/cefode-chromium,bright-sparks/chromium-spacewalk,timopulkkinen/BubbleFish,axinging/chromium-crosswalk,pozdnyakov/chromium-crosswalk,littlstar/chromium.src,M4sse/chromium.src,junmin-zhu/chromium-rivertrail,ondra-novak/chromium.src,ChromiumWebApps/chromium,M4sse/chromium.src,keishi/chromium,Pluto-tv/chromium-crosswalk,crosswalk-project/chromium-crosswalk-efl,hujiajie/pa-chromium,ltilve/chromium,PeterWangIntel/chromium-crosswalk,zcbenz/cefode-chromium,mohamed--abdel-maksoud/chromium.src,hujiajie/pa-chromium,robclark/chromium,patrickm/chromium.src,mohamed--abdel-maksoud/chromium.src,pozdnyakov/chromium-crosswalk,Chilledheart/chromium,patrickm/chromium.src,timopulkkinen/BubbleFish,fujunwei/chromium-crosswalk,junmin-zhu/chromium-rivertrail,mogoweb/chromium-crosswalk,hgl888/chromium-crosswalk-efl,Chilledheart/chromium,zcbenz/cefode-chromium,markYoungH/chromium.src,ondra-novak/chromium.src,junmin-zhu/chromium-rivertrail,patrickm/chromium.src,dednal/chromium.src,crosswalk-project/chromium-crosswalk-efl,markYoungH/chromium.src,axinging/chromium-crosswalk,zcbenz/cefode-chromium,patrickm/chromium.src,junmin-zhu/chromium-rivertrail,bright-sparks/chromium-spacewalk,Just-D/chromium-1,nacl-webkit/chrome_deps,dednal/chromium.src,krieger-od/nwjs_chromium.src,pozdnyakov/chromium-crosswalk,Chilledheart/chromium,Jonekee/chromium.src,ltilve/chromium,bright-sparks/chromium-spacewalk,Jonekee/chromium.src,Just-D/chromium-1,pozdnyakov/chromium-crosswalk,ChromiumWebApps/chromium,hgl888/chromium-crosswalk-efl,Just-D/chromium-1,mogoweb/chromium-crosswalk,axinging/chromium-crosswalk,rogerwang/chromium,anirudhSK/chromium,dushu1203/chromium.src,Fireblend/chromium-crosswalk,hgl888/chromium-crosswalk,ondra-novak/chromium.src,PeterWangIntel/chromium-crosswalk,keishi/chromium,hgl888/chromium-crosswalk-efl,chuan9/chromium-crosswalk,robclark/chromium,hgl888/chromium-crosswalk-efl,fujunwei/chromium-crosswalk,bright-sparks/chromium-spacewalk,fujunwei/chromium-crosswalk,jaruba/chromium.src,ltilve/chromium,axinging/chromium-crosswalk,ltilve/chromium,Jonekee/chromium.src,hujiajie/pa-chromium,chuan9/chromium-crosswalk,hujiajie/pa-chromium,keishi/chromium,bright-sparks/chromium-spacewalk,robclark/chromium,hujiajie/pa-chromium,ChromiumWebApps/chromium,markYoungH/chromium.src,anirudhSK/chromium,dednal/chromium.src,jaruba/chromium.src,M4sse/chromium.src,junmin-zhu/chromium-rivertrail,Just-D/chromium-1,ltilve/chromium,keishi/chromium,hujiajie/pa-chromium,Pluto-tv/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,Jonekee/chromium.src,M4sse/chromium.src,Fireblend/chromium-crosswalk,junmin-zhu/chromium-rivertrail,chuan9/chromium-crosswalk,robclark/chromium,pozdnyakov/chromium-crosswalk,Pluto-tv/chromium-crosswalk,junmin-zhu/chromium-rivertrail,anirudhSK/chromium,dednal/chromium.src,TheTypoMaster/chromium-crosswalk,dushu1203/chromium.src,patrickm/chromium.src,littlstar/chromium.src,Just-D/chromium-1,ChromiumWebApps/chromium,crosswalk-project/chromium-crosswalk-efl,mogoweb/chromium-crosswalk,markYoungH/chromium.src,jaruba/chromium.src,mohamed--abdel-maksoud/chromium.src,nacl-webkit/chrome_deps,robclark/chromium,dushu1203/chromium.src,anirudhSK/chromium,Just-D/chromium-1,TheTypoMaster/chromium-crosswalk,fujunwei/chromium-crosswalk,anirudhSK/chromium,jaruba/chromium.src,chuan9/chromium-crosswalk,dushu1203/chromium.src,dushu1203/chromium.src,Jonekee/chromium.src,TheTypoMaster/chromium-crosswalk,robclark/chromium,mogoweb/chromium-crosswalk,chuan9/chromium-crosswalk,bright-sparks/chromium-spacewalk,rogerwang/chromium,mogoweb/chromium-crosswalk,anirudhSK/chromium,jaruba/chromium.src,nacl-webkit/chrome_deps,timopulkkinen/BubbleFish,patrickm/chromium.src,markYoungH/chromium.src,TheTypoMaster/chromium-crosswalk,mohamed--abdel-maksoud/chromium.src,Chilledheart/chromium,timopulkkinen/BubbleFish,mohamed--abdel-maksoud/chromium.src,patrickm/chromium.src,mohamed--abdel-maksoud/chromium.src,PeterWangIntel/chromium-crosswalk,dushu1203/chromium.src,pozdnyakov/chromium-crosswalk,Fireblend/chromium-crosswalk,dushu1203/chromium.src,dednal/chromium.src,keishi/chromium,Chilledheart/chromium,krieger-od/nwjs_chromium.src,TheTypoMaster/chromium-crosswalk,hgl888/chromium-crosswalk,rogerwang/chromium,fujunwei/chromium-crosswalk,mohamed--abdel-maksoud/chromium.src,nacl-webkit/chrome_deps,mogoweb/chromium-crosswalk,dednal/chromium.src,Fireblend/chromium-crosswalk,Chilledheart/chromium,littlstar/chromium.src,nacl-webkit/chrome_deps,TheTypoMaster/chromium-crosswalk,Jonekee/chromium.src,dushu1203/chromium.src,jaruba/chromium.src,timopulkkinen/BubbleFish,jaruba/chromium.src,Pluto-tv/chromium-crosswalk,nacl-webkit/chrome_deps,axinging/chromium-crosswalk,hgl888/chromium-crosswalk-efl,zcbenz/cefode-chromium,chuan9/chromium-crosswalk,axinging/chromium-crosswalk,mogoweb/chromium-crosswalk,zcbenz/cefode-chromium,dednal/chromium.src,krieger-od/nwjs_chromium.src,ChromiumWebApps/chromium,bright-sparks/chromium-spacewalk,jaruba/chromium.src,hgl888/chromium-crosswalk-efl,PeterWangIntel/chromium-crosswalk,Fireblend/chromium-crosswalk,hgl888/chromium-crosswalk,dednal/chromium.src,Fireblend/chromium-crosswalk,anirudhSK/chromium,Just-D/chromium-1,hgl888/chromium-crosswalk,anirudhSK/chromium,pozdnyakov/chromium-crosswalk,markYoungH/chromium.src,Jonekee/chromium.src,rogerwang/chromium,krieger-od/nwjs_chromium.src,anirudhSK/chromium,ondra-novak/chromium.src,hujiajie/pa-chromium,ChromiumWebApps/chromium,bright-sparks/chromium-spacewalk,PeterWangIntel/chromium-crosswalk,ChromiumWebApps/chromium,Jonekee/chromium.src,junmin-zhu/chromium-rivertrail,krieger-od/nwjs_chromium.src,nacl-webkit/chrome_deps,ChromiumWebApps/chromium,hgl888/chromium-crosswalk-efl,mogoweb/chromium-crosswalk,axinging/chromium-crosswalk,dushu1203/chromium.src,timopulkkinen/BubbleFish,hgl888/chromium-crosswalk,Pluto-tv/chromium-crosswalk,markYoungH/chromium.src,Jonekee/chromium.src,keishi/chromium,jaruba/chromium.src,chuan9/chromium-crosswalk,fujunwei/chromium-crosswalk,keishi/chromium,ChromiumWebApps/chromium,nacl-webkit/chrome_deps,mogoweb/chromium-crosswalk,hujiajie/pa-chromium,M4sse/chromium.src,mogoweb/chromium-crosswalk,anirudhSK/chromium,mohamed--abdel-maksoud/chromium.src,ondra-novak/chromium.src,Fireblend/chromium-crosswalk,ltilve/chromium,nacl-webkit/chrome_deps,crosswalk-project/chromium-crosswalk-efl,crosswalk-project/chromium-crosswalk-efl,ondra-novak/chromium.src,dushu1203/chromium.src,pozdnyakov/chromium-crosswalk