Trac 53 minw update

http://libwebsockets.org/trac/libwebsockets/ticket/53
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 595d972..c591149 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -310,7 +310,11 @@
 
 
 if (CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUCXX)
+    if (UNIX)
 	set( CMAKE_C_FLAGS "-Wall -Werror -O4 -fvisibility=hidden ${CMAKE_C_FLAGS}" )
+    else(UNIX)
+	set( CMAKE_C_FLAGS "-Wall -O4 -fvisibility=hidden ${CMAKE_C_FLAGS}" )
+    endif(UNIX)
 endif ()
 
 source_group("Headers Private"  FILES ${HDR_PRIVATE})