Bug#887597: adonthell: Detect freetype using pkg-config

[Hugh McMaster]

On Sunday, 21 January 2018 1:09 AM, Simon McVittie wrote:
> AC_CHECK_FT2 is just as much an API as freetype-config is. If that API
> is to be removed, please do a mass-bug-filing for that too.

Thanks, Simon. I'll do this too.