Vala and pkg-config

[Jürg Billeter <j bitron ch>]

Vincent brought to my attention that there are some packages out there
that use pkg-config to check for the presence and version of the Vala
compiler. However, this is wrong and should be removed in all affected
packages as soon as possible.

The pkg-config file is installed for libvala, which is an unstable
library that is only needed by development tools to, e.g., provide code
completion in IDEs. All other Vala applications and libraries should not
use or link to libvala and should therefore also not use the pkg-config
file.

I've changed the pkg-config name in the 0.9.5 release to vala-0.10 to
support parallel installation with future release series. As the
pkg-config file is only meant to be used with the unstable libvala
library and I wasn't aware of it being used for the compiler itself,
this caused more fallout than expected. Sorry about that.

If you use automake 1.11+, you can use AM_PROG_VALAC([0.9.5]) in your
configure.ac to check for a minimum Vala compiler version. Vala 0.9.5
also comes with a VALA_CHECK_PACKAGES macro, which you can use in
configure.ac to check for bindings.

To make the lives of developers, testers, and packagers not harder than
necessary, please check as soon as possible that your Vala-using package
does not use pkg-config for Vala compiler checks.

Thanks,
Jürg