cmake HAVE_WSAEWOULDBLOCK examples

ShadowsocksR-Live/shadowsocksr-native cmake/configure.cmake :115 

check_symbol_exists ( WSAEWOULDBLOCK "winerror.h" HAVE_WSAEWOULDBLOCK )

ShadowsocksR-Live/shadowsocksr-native cmake/configure.cmake :185 

elseif(${HAVE_WSAEWOULDBLOCK})