Merge pull request Tencent#35 from zagnix/master

fix compile for centos

Author: leiffyli

CMakeLists.txt

@@ -41,7 +41,7 @@ set_target_properties(colib_shared PROPERTIES VERSION ${LIBCO_VERSION} SOVERSION
 # Macro for add example target
 macro(add_example_target EXAMPLE_TARGET)
     add_executable("example_${EXAMPLE_TARGET}" "example_${EXAMPLE_TARGET}.cpp")
-    target_link_libraries("example_${EXAMPLE_TARGET}" colib_static)
+    target_link_libraries("example_${EXAMPLE_TARGET}" colib_static pthread dl)
 endmacro(add_example_target)
 
 add_example_target(closure)

example_echosvr.cpp

@@ -33,6 +33,7 @@
 #include <arpa/inet.h>
 #include <unistd.h>
 #include <errno.h>
+#include <sys/wait.h>
 
 using namespace std;
 struct task_t