Only remove previous warning for gcc.

CMakeLists.txt

@@ -17,6 +17,10 @@ if (WINDOWS)
     ADD_DEFINITIONS(-D WINDOWS=1)
 endif (WINDOWS)
 
+if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+    add_compile_options(-Wno-error=cast-function-type)
+endif ()
+
 message(STATUS "Using:
 \t C ${CMAKE_C_COMPILER}
 \t C++ ${CMAKE_CXX_COMPILER}