Shortening buffer accessors: rename buffer->out_string to buffer->out_info

src/hb-buffer-private.hh

diff --git a/src/hb-buffer-private.hh b/src/hb-buffer-private.hh
index 16d3e19..bd291e6 100644
--- a/src/hb-buffer-private.hh
+++ b/src/hb-buffer-private.hh
@@ -115,7 +115,7 @@
   unsigned int in_pos;
 
   hb_internal_glyph_info_t     *info;
-  hb_internal_glyph_info_t     *out_string;
+  hb_internal_glyph_info_t     *out_info;
   hb_internal_glyph_position_t *positions;
 
   /* Other stuff */