FindFreetype: Remove duplicates in FREETYPE_INCLUDE_DIRS

In Freetype 2.5 the paths for FREETYPE_INCLUDE_DIR_ft2build and
FREETYPE_INCLUDE_DIR_freetype2 are the same
Merge topic 'FindFreetype-2.5' into next

9b08e3f FindFreetype: Remove duplicates in FREETYPE_INCLUDE_DIRS