Fix harmless warning about double to long long conversion.

Work around g++ -Wconversion warning by writing out the casts explicitly.

A better solution would be to have wxLongLong::FromDouble() static function
but it would have to be done after 2.9.2.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@68152 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/mediactrl_am.cpp

@@ -2020,7 +2020,15 @@ wxLongLong wxAMMediaBackend::GetDuration()
 
         case S_OK:
             // outDuration is in seconds, we need milliseconds
-            return static_cast<wxLongLong>(outDuration * 1000);
+#ifdef wxLongLong_t
+            return static_cast<wxLongLong_t>(outDuration * 1000);
+#else
+            // In principle it's possible to have video of duration greater
+            // than ~1193 hours which corresponds LONG_MAX in milliseconds so
+            // cast to wxLongLong first and multiply by 1000 only then to avoid
+            // the overflow (resulting in maximal duration of ~136 years).
+            return wxLongLong(static_cast<long>(outDuration)) * 1000;
+#endif
     }
 }