Remove extraneous semicolons after wxDECL_FOR_STRICT_MINGW32().

This macro shouldn't be followed by a semicolon because it can be empty, so
remove the extra semicolons to avoid -Wpedantic g++ warnings about it.

include/wx/msw/gccpriv.h

@@ -159,7 +159,7 @@
         standard headers (e.g. <algorithm>) and we don't want to duplicate this
         hack everywhere this happens.
      */
-    wxDECL_FOR_STRICT_MINGW32(double, _hypot, (double, double));
+    wxDECL_FOR_STRICT_MINGW32(double, _hypot, (double, double))
 #else
     #define wxDECL_FOR_STRICT_MINGW32(rettype, func, params)
 #endif