Fixed typo (thanks @Clownacy!)

CMakeLists.txt

@@ -174,7 +174,7 @@ if(USE_CLANG OR USE_GCC OR USE_INTELCC OR USE_TCC OR MSVC_VERSION GREATER 1400)
 endif()
 
 set(SDL_GCC_ATOMICS_DEFAULT OFF)
-if(USE_GCC OR USE_CLANG OR USE_INTELCC OR USE_QCC OR TCC)
+if(USE_GCC OR USE_CLANG OR USE_INTELCC OR USE_QCC OR USE_TCC)
   set(SDL_GCC_ATOMICS_DEFAULT ON)
 endif()