[Mesa-maintainers] Mesa master requires expat which ships with a .pc file

[Emil Velikov]

[Adding a couple of CentOS guys]

Hi all,

With the following Mesa commit [1] I dropped a workaround we had for
10+year old version of expat that lack a expat.pc file.
The file was introduced with v 2.1 released 2012, which is available
even in Debian oldoldstable.

Seems like I've missed the CentOS/RHEL 6 series which still uses 2.0 by default.

Which brings the questions:
- Does your platform ship expat 2.1/expat.pc file?
- How many distributions/people are affected?

If it's more than the odd build-test bot, we could opt for Vinson's
workaround [2].
Alternatively can the affected platforms/setups use a local workaround?

Possible solutions include:
 - create/cp/symlink a expat.pc file, and point PKG_CONFIG_PATH to it
 - set EXPAT_CFLAGS and EXPAT_LIBS alongside/prior to calling configure

Please, let's not dwell into distributions' packaging decisions and
focus on how many uses-cases we have.

Thanks
Emil

[1] https://cgit.freedesktop.org/mesa/mesa/commit/?id=5c007203b73da88b9e76ce28027c6d27661e45b1
[2] https://patchwork.freedesktop.org/patch/170551/