Silence implicit-fallthrough warning in GCC when FALLTHROUGH macro is used

nyalldawson · nyalldawson · commit 3c1bdf059d1e · 2017-07-13T08:17:57.000+10:00
diff --git a/src/core/qgis.h b/src/core/qgis.h
@@ -385,6 +385,8 @@ typedef unsigned long long qgssize;
 
 #if defined(__clang__)
 #define FALLTHROUGH //[[clang::fallthrough]]
+#elif defined(__GNUC__)
+#define FALLTHROUGH [[gnu::fallthrough]];
 #else
 #define FALLTHROUGH
 #endif
