tdf#69254: Tweak mapping from CoreText weight to our FontWeight a bit

Make the mapping of light weights more likely to hit different enum
values for slightly different weights.

We want to be able to distinguish between for instance Overpass Light
(with weight -0.4) and Overpass ExtraLight (with weight -0.5).

Change-Id: If83fbce68149b267a49ef9bcb6624d8790de7c56
Reviewed-on: https://gerrit.libreoffice.org/48409Reviewed-by: Tor Lillqvist <tml@collabora.com>
Tested-by: Tor Lillqvist <tml@collabora.com>

vcl/quartz/ctfonts.cxx

@@ -392,7 +392,7 @@ FontAttributes DevFontFromCTFontDescriptor( CTFontDescriptorRef pFD, bool* bFont
     }
     else if( fWeight < 0 )
     {
-        nInt = rint(WEIGHT_NORMAL + fWeight * ((WEIGHT_NORMAL - WEIGHT_THIN)/0.9));
+        nInt = rint(WEIGHT_NORMAL + fWeight * ((WEIGHT_NORMAL - WEIGHT_THIN)/0.8));
         if( nInt < WEIGHT_THIN )
         {
             nInt = WEIGHT_THIN;