freetype: enable out-of-tree builds, and use host zlib
Add a few ${S} and ${B} to make out of tree builds work, and stop using
autotools-brokensep. Annoyingly we still need to use a custom do_configure so
add a comment explaining why so someone else doesn't spend 30 minutes trying to
make it work.
Whilst here add a small patch so we don't need to tell the build where libtool
is, and remove class-native do_configure as it doesn't appear to be required
anymore.
At this point I started to get carried away.
The do_compile_prepend is redundant now that configure is being told what
compiler to use for build tools, so remove that.
Instead of using the integrated zlib fork, add a PACKAGECONFIG to use the zlib
we build and enable that by default. Also add a disabled PACKAGECONFIG for
bzip2 support.
Signed-off-by: Ross Burton <ross.burton@intel.com>
