Fix compilation warnings.
Fix compilation warnings.

* test/test_context.c
  (test_serf_connection_request_create,
  test_serf_connection_priority_request_create,
  test_serf_closed_connection, test_serf_setup_proxy,
  test_keepalive_limit_one_by_one,
  test_keepalive_limit_one_by_one_and_burst): Make functions static.

idomon/serf,KyleSanderson/serf,x-clone/serf,soufianeEL/serf,x-clone/serf,lazysoez/serf,TommyU/serf,muthusuba/serf,wzugang/serf,krime/serf,wzugang/serf,stoneCC/serf,muthusuba/serf,idomon/serf,krime/serf,google-code-export/serf,justinweb/serf,KyleSanderson/serf,google-code-export/serf,lazysoez/serf,pengdu/serf,zhengcq315/serf,sworda/serf,alex1818/serf,yesoce/serf,yesoce/serf,sworda/serf,yesoce/serf,idomon/serf,liuzongquan/serf,liuzongquan/serf,sworda/serf,Manouchehri/serf,soufianeEL/serf,zhupan/serf,soufianeEL/serf,KyleSanderson/serf,blueszhangsh/serf,liuzongquan/serf,x-clone/serf,liuzongquan/serf,blueszhangsh/serf,blueszhangsh/serf,SirJson/serf,KyleSanderson/serf,zhengcq315/serf,stoneCC/serf,muthusuba/serf,SirJson/serf,zhupan/serf,krime/serf,pengdu/serf,pengdu/serf,justinweb/serf,zhengcq315/serf,stoneCC/serf,wzugang/serf,alex1818/serf,idomon/serf,zhengcq315/serf,muthusuba/serf,wzugang/serf,TommyU/serf,pengdu/serf,lazysoez/serf,TommyU/serf,TommyU/serf,justinweb/serf,sworda/serf,SirJson/serf,zhupan/serf,alex1818/serf,x-clone/serf,blueszhangsh/serf,Manouchehri/serf,Manouchehri/serf,SirJson/serf,stoneCC/serf,zhupan/serf,yesoce/serf,justinweb/serf,lazysoez/serf,google-code-export/serf,krime/serf,alex1818/serf,Manouchehri/serf,google-code-export/serf,soufianeEL/serf