Fix compilation errors on Fedora 20.
Fix compilation errors on Fedora 20.

peerconnection_jni.cc: syscall() comes from <unistd.h>
RTPtimeshift.cc: char* being compared to 0 instead of the atoi() of it
rtp_payload_registry_unittest.cc: avoid narrowing int to uint32.

BUG=2700
R=andrew@webrtc.org, fischman@webrtc.org, henrik.lundin@webrtc.org, henrike@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/5019004

Patch from Victor Costan <costan@gmail.com>.

git-svn-id: a556c8bde68cedbc0208a1ffc78b06e9cd07f676@5248 4adac7df-926f-26a2-2b94-8c16560cd09d

bpsinc-native/src_third_party_libjingle_source_talk,dcpang/fatline-libjingle,AOSPU/external_chromium_org_third_party_libjingle_source_talk,android-ia/platform_external_chromium_org_third_party_libjingle_source_talk,xin3liang/platform_external_chromium_org_third_party_libjingle_source_talk,bpsinc-native/src_third_party_libjingle_source_talk,bpsinc-native/src_third_party_libjingle_source_talk,sippet/talk,xin3liang/platform_external_chromium_org_third_party_libjingle_source_talk,geekboxzone/lollipop_external_chromium_org_third_party_libjingle_source_talk,bpsinc-native/src_third_party_libjingle_source_talk,xin3liang/platform_external_chromium_org_third_party_libjingle_source_talk,AOSPU/external_chromium_org_third_party_libjingle_source_talk,bpsinc-native/src_third_party_libjingle_source_talk,android-ia/platform_external_chromium_org_third_party_libjingle_source_talk,dcpang/fatline-libjingle,AOSPU/external_chromium_org_third_party_libjingle_source_talk,Omegaphora/external_chromium_org_third_party_libjingle_source_talk,Omegaphora/external_chromium_org_third_party_libjingle_source_talk,dcpang/fatline-libjingle,Omegaphora/external_chromium_org_third_party_libjingle_source_talk,geekboxzone/lollipop_external_chromium_org_third_party_libjingle_source_talk,bpsinc-native/src_third_party_libjingle_source_talk,geekboxzone/lollipop_external_chromium_org_third_party_libjingle_source_talk,android-ia/platform_external_chromium_org_third_party_libjingle_source_talk,android-ia/platform_external_chromium_org_third_party_libjingle_source_talk,Omegaphora/external_chromium_org_third_party_libjingle_source_talk,sippet/talk,sippet/talk,geekboxzone/lollipop_external_chromium_org_third_party_libjingle_source_talk,AOSPU/external_chromium_org_third_party_libjingle_source_talk,sippet/talk,xin3liang/platform_external_chromium_org_third_party_libjingle_source_talk,dcpang/fatline-libjingle,android-ia/platform_external_chromium_org_third_party_libjingle_source_talk,xin3liang/platform_external_chromium_org_third_party_libjingle_source_talk,geekboxzone/lollipop_external_chromium_org_third_party_libjingle_source_talk,android-ia/platform_external_chromium_org_third_party_libjingle_source_talk,Omegaphora/external_chromium_org_third_party_libjingle_source_talk,dcpang/fatline-libjingle,Omegaphora/external_chromium_org_third_party_libjingle_source_talk,AOSPU/external_chromium_org_third_party_libjingle_source_talk,sippet/talk