Initialise more fields, especially mfFakeDPIScale

Now the iOS app displays the test document successfully again.

Change-Id: I71aeacc50e51a28ba1e8b67c7da42da0c848f997

vcl/coretext/salgdi2.cxx

@@ -290,7 +290,9 @@ AquaSalGraphics::AquaSalGraphics()
     , mbVirDev( false )
     , mbWindow( false )
 #else
-    : mpMacFontData( NULL )
+    : mrContext( NULL )
+    , mfFakeDPIScale( 1.0 )
+    , mpMacFontData( NULL )
     , mpMacTextStyle( NULL )
     , maTextColor( COL_BLACK )
     , mbNonAntialiasedText( false )