compat: merge compat library into EAL

compat: merge compat library into EAL

Since compat library is only a single header, we can easily move it into
the EAL common headers instead of tracking it separately. The downside of
this is that it becomes a little more difficult to have any libs that are
built before EAL depend on it. Thankfully, this is not a major problem as
the only library which uses rte_compat.h and is built before EAL (kvargs)
already has the path to the compat.h header file explicitly called out as
an include path.

However, to ensure that we don't hit problems later with this, we can add
EAL common headers folder to the global include list in the meson build
which means that all common headers can be safely used by all libraries, no
matter what their build order.

As a side-effect, this patch also fixes an issue with building on BSD using
meson, due to compat lib no longer needing to be listed as a dependency.

Fixes: a8499f65a1d1 ("log: add missing experimental tag")
Cc: stable@dpdk.org
Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Reviewed-by: David Marchand <david.marchand@redhat.com>
Tested-by: David Marchand <david.marchand@redhat.com>
Tested-by: Anatoly Burakov <anatoly.burakov@intel.com>
Acked-by: Thomas Monjalon <thomas@monjalon.net>