freetype: avoid very large fonts in portrait mode

Either when the video is in portrait mode or when the subtitles
are shown in the black bars and the video area is in portrait mode,
the text can become very large just because we apply a percentage base on
the output height.

We switch mode when the height becomes bigger than the width
so there's a continuity in the ratio when growing/shrinking the
video in one direction or the other.

modules/text_renderer/freetype/platform_fonts.c

@@ -554,7 +554,11 @@ int ConvertToLiveSize( filter_t *p_filter, const text_style_t *p_style )
     }
     else if ( p_style->f_font_relsize )
     {
-        i_font_size = (int) p_filter->fmt_out.video.i_height * p_style->f_font_relsize / 100;
+        unsigned area_height = p_filter->fmt_out.video.i_height;
+        if (p_filter->fmt_out.video.i_height > p_filter->fmt_out.video.i_width )
+            // portrait mode leads to very large text
+            area_height = p_filter->fmt_out.video.i_width;
+        i_font_size = (int) area_height * p_style->f_font_relsize / 100;
     }
 
     if( p_sys->i_scale != 100 )