I tried compiling the latest stable release on Arch linux which unfortunately failed.
The problem seems to be caused by a recent change in the include guard naming in freetype where leading underscores (__) have been removed:
sourceforge.net/projects/freetype/files/freetype2/2.6.3/
I changed the file uppsrc/plugin/FT_fontsys/ft2build.h and added the new macro name which did the trick for me but perhaps it should be done in another way.