Correctly handle S_FALSE return value of IActiveMovie::get_Duration().

IActiveMovie::get_Duration() can return S_FALSE in which case outDuration
isn't initialized and so wxAMMediaBackend::GetDuration() would return a
completely wrong value.

Fix this by returning 0 from it instead which seems like the only reasonable
thing to do (in the absence of documentation of this interface it's not really
clear what does S_FALSE return value mean nor why didn't it return it before).

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65845 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/mediactrl_am.cpp

@@ -2009,18 +2009,19 @@ wxLongLong wxAMMediaBackend::GetDuration()
 {
     double outDuration;
     HRESULT hr = GetAM()->get_Duration(&outDuration);
-    if(FAILED(hr))
+    switch ( hr )
     {
+        default:
             wxAMLOG(hr);
+            // fall through
+
+        case S_FALSE:
             return 0;
+
+        case S_OK:
+            // outDuration is in seconds, we need milliseconds
+            return outDuration * 1000;
     }
-
-    // h,m,s,milli - outDuration is in 1 second (double)
-    outDuration *= 1000;
-    wxLongLong ll;
-    ll.Assign(outDuration);
-
-    return ll;
 }
 
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