Fix set C compiler flags bug

Author: latchdevel

CMakeLists.txt

@@ -41,7 +41,7 @@ if(CMAKE_BUILD_TYPE STREQUAL "DEBUG")
 endif()
 
 # Set C compiler flags
-if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+if(CMAKE_COMPILER_IS_GNUC OR CMAKE_C_COMPILER_ID MATCHES "Clang")
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-deprecated-declarations")
 elseif(MSVC)
   set(MSVC_DISABLED_WARNINGS_LIST