Disable correct compiler-warning: unused-function.

code/Common/StbCommon.h

@@ -45,7 +45,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #pragma warning(disable : 4505)
 #else
 #pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wunused-variable"
+#pragma GCC diagnostic ignored "-Wunused-function"
 #endif
 
 #define STB_IMAGE_STATIC