fdo#61272: Do the mapping correctly both for WMF and EMF.

Turns out that for the WMF, we already had everything set up correctly, we
were just overwriting the right settings with default data again :-) - fix
that.

Change-Id: I14b0c12b10f58eb7031f9da712dee76344c75159

vcl/source/filter/wmf/winmtf.cxx

@@ -1972,7 +1972,7 @@ void WinMtfOutput::SetRefMill( const Size& rSize )
 void WinMtfOutput::SetMapMode( sal_uInt32 nMapMode )
 {
     mnMapMode = nMapMode;
-    if ( nMapMode == MM_TEXT )
+    if ( nMapMode == MM_TEXT && !mbIsMapWinSet )
     {
         mnWinExtX = mnDevWidth;
         mnWinExtY = mnDevHeight;