winvlc: silence unused warnings

If breakpad is not used, the crash_handling variable is not used too,
but as it's used otherwise this should be silenced.

(cherry picked from commit 81c60915)
Signed-off-by: Steve Lhomme <robux4@ycbcr.xyz>

bin/winvlc.c

@@ -221,6 +221,8 @@ int WINAPI WinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance,
         CheckCrashDump( &path[0] );
         eh = InstallCrashHandler( &path[0] );
     }
+#else
+    (void)crash_handling;
 #endif
 
     _setmode( _fileno( stdin ), _O_BINARY ); /* Needed for pipes */