Update fontconfig dependancy

Summary: The version we currently use is not compatible with recent version of glibc, so we are updating.

Test Plan:

make -C ../depends HOST=i686-pc-linux-gnu

Reviewers: schancel, jasonbcox, #bitcoin_abc, zquestz

Reviewed By: schancel, jasonbcox, #bitcoin_abc, zquestz

Differential Revision: https://reviews.bitcoinabc.org/D852