minui: graphics: add ability to query font size

Change-Id: I5e8f477b7b205794f2975f12e6b6010c177f6052
Signed-off-by: Dima Zavin <dima@android.com>
diff --git a/minui/minui.h b/minui/minui.h
index 567d421..5496b09 100644
--- a/minui/minui.h
+++ b/minui/minui.h
@@ -32,6 +32,7 @@
 void gr_fill(int x, int y, int w, int h);
 int gr_text(int x, int y, const char *s);
 int gr_measure(const char *s);
+void gr_font_size(int *x, int *y);
 
 void gr_blit(gr_surface source, int sx, int sy, int w, int h, int dx, int dy);
 unsigned int gr_get_width(gr_surface surface);