fontconfig: remove unexplainable and broken build tweaking

fontconfig: remove unexplainable and broken build tweaking

The build flag twiddling in do_configure_append was unexplainable and clearly
wrong (native flags for a cross build), remove it all.

Parallel make appears to be working now, so enable it.

The tarball doesn't contain read only sources, remove the unpack hacking.

The pkgconfig doesn't need patching as the freetype link lines are the same.

Don't need to specify where freetype is, it's found automatically.

Merge fontconfig-util-dbg into fontconfig-dbg.

Don't export HASDOCBOOK, --disable-docs is sufficient to turn off documentation
building.

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