Revert "fontconfig: enable 64 bit file support"

Fontconfig doesn't need to be passed large file flags through CPPFLAGS because
it's configure script uses AC_SYS_LARGEFILE.

This reverts commit 5a49a24d35794fcf9e3895469a67db992a52305e.

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>