Fix FT_Get_Kerning using char codes instead of glyph indices.

src/modules/font/freetype/TrueTypeRasterizer.cpp

@@ -168,7 +168,11 @@ bool TrueTypeRasterizer::hasGlyph(uint32 glyph) const
 float TrueTypeRasterizer::getKerning(uint32 leftglyph, uint32 rightglyph) const
 {
 	FT_Vector kerning = {};
-	FT_Get_Kerning(face, leftglyph, rightglyph, FT_KERNING_DEFAULT, &kerning);
+	FT_Get_Kerning(face,
+	               FT_Get_Char_Index(face, leftglyph),
+	               FT_Get_Char_Index(face, rightglyph),
+	               FT_KERNING_DEFAULT,
+	               &kerning);
 	return float(kerning.x >> 6);
 }