Fix accessibility support in wxMSW.

Return the correct result from handing WM_GETOBJECT message.

Closes #17058.

(this is a backport of 6a435345f5 from master)

docs/changes.txt

@@ -612,6 +612,7 @@ wxGTK:
 wxMSW:
 
 - Fix compilation with g++ 4.9 in non-C++11 mode.
+- Fix regression in accessibility support (Leland Lucius).
 - Fix regression in wxDC drawing with bottom-to-top y axis (Artur Wieczorek).
 - Fix compilation with C++Builder XE compiler (Nichka).
 - Fix best height of wxSlider with labels but without ticks (Artur Wieczorek).

src/msw/window.cpp

@@ -3386,7 +3386,8 @@ wxWindowMSW::MSWHandleMessage(WXLRESULT *result,
 
                 if (dwObjId == (LPARAM)OBJID_CLIENT && GetOrCreateAccessible())
                 {
-                    return LresultFromObject(IID_IAccessible, wParam, (IUnknown*) GetAccessible()->GetIAccessible());
+                    processed = true;
+                    rc.result = LresultFromObject(IID_IAccessible, wParam, (IUnknown*) GetAccessible()->GetIAccessible());
                 }
                 break;
             }