Use smaller default font on iOS (in practice used for dialogs in the iOS app)

I suspected all the time that just one single-line change will be what
is needed to make the dialogs look mostly sane. (Especially Format >
Character... and Format > Paragraph...) No exotic hacks were needed
after all, even though I experimented with more or less crazy ones for
several days before I thought of changing this font size 14 to
something smaller.

The problem was apparently simply that with the larger default font,
the dialog controls didn't fit properly in the space provided.
Especially the four combo boxes on one line in the Font page were
problematic. (It has three such lines of combo boxes.)

Apparently the dialog machinery isn't especially good at reducing
width of controls. The Size control shrunk to (almost?) zero width and
was not visible, the Style control was too narrow to be usable, but
the Language control was left as unnecessarily wide.

Note that this is a cherry-pick from our vendor branch (cp-6.0). It
hasn't actually been tested as the iOS app doesn't work at the moment
if built from the master branches of online and core.

(cherry picked from commit 96dce784)

Change-Id: If5675856345be2ae502346e8c097ef04216e2986

vcl/ios/iosinst.cxx

@@ -107,7 +107,7 @@ public:
     virtual void UpdateSettings( AllSettings &rSettings ) override
     {
         // Clobber the UI fonts
-        vcl::Font aFont( OUString( "Helvetica" ), Size( 0, 14 ) );
+        vcl::Font aFont( OUString::fromUtf8( [[[UIFont systemFontOfSize:7] familyName] UTF8String] ), Size( 0, 7 ) );
 
         StyleSettings aStyleSet = rSettings.GetStyleSettings();
         aStyleSet.SetAppFont( aFont );