sfnt2fnt: Take into account external leading when calculating the font point size.

This makes the dfPoints field of the Japanese System font match the Windows one.
diff --git a/tools/sfnt2fnt.c b/tools/sfnt2fnt.c
index 6880ee8..de19d8f 100644
--- a/tools/sfnt2fnt.c
+++ b/tools/sfnt2fnt.c
@@ -414,7 +414,7 @@
     info->dfCharTable[i].offset = start + (width_bytes * ppem);
 
     info->hdr.fi.dfType = 0;
-    info->hdr.fi.dfPoints = ((ppem - il) * 72 + dpi/2) / dpi;
+    info->hdr.fi.dfPoints = ((ppem - il - el) * 72 + dpi/2) / dpi;
     info->hdr.fi.dfVertRes = dpi;
     info->hdr.fi.dfHorizRes = dpi;
     info->hdr.fi.dfAscent = ascent;