devtools: test 32-bit build

devtools: test 32-bit build

It's reasonably common for patches to have issues when built on 32-bits, so
to prevent this, we can add a 32-bit build (if supported) to the
"test-meson-builds.sh" script. The tricky bit is using a valid
PKG_CONFIG_LIBDIR, so for now we use two common possibilities for where that
should point to in order to get a successful build.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Signed-off-by: Thomas Monjalon <thomas@monjalon.net>