Log Message:
SDL2_ttf: update to 2.0.15.

2.0.15:
Sam Lantinga - Fri Oct 26 13:26:54 PDT 2018
 * Updated to FreeType version 2.9.1
Sam Lantinga - Sun Sep 10 00:18:45 PDT 2017
 * Text rendering functions now use the alpha component of the text colors
Sam Lantinga - Sat Sep  9 22:21:55 PDT 2017
 * Added support for characters greater than 0xFFFF (e.g. emoji) in the UTF-8 APIs