mesa: make zlib dependency a PACKAGECONFIG

mesa: make zlib dependency a PACKAGECONFIG

zlib is a mesa meson feature which can be disabled so let's make it a
PACKAGECONFIG.

The motivation actually isn't about disabling it (though we now could as
it's only required for a few things) but rather that this dependency is
a non-native one.

The issue is when a native-only (-native recipe name suffix + inherit
native) recipe includes mesa.inc, it'll include the DEPENDS as well but
will then depend on a non-native recipe because BitBake doesn't add a
suffix to dependencies listed in DEPENDS for native-only recipes like it
does for recipes with BBCLASSEXTEND = native. This is a way to
circumvent the issue by making the dependency a PACKAGECONFIG dependency
such that the listed DEPENDS (third parameter) will be properly modified
by BitBake to have the native variant of the recipe pulled in. See[1]
for more info on why this is needed.

This is in preparation for the addition of a mesa-tools-native
native-only package which will include mesa.inc.

[1] https://lore.kernel.org/openembedded-core/07cd1d3c-4d67-4e60-b3d3-75953784f70f@cherry.de/

Signed-off-by: Quentin Schulz <quentin.schulz@cherry.de>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>