Inconsistency in installation of syscache_info.h

I happened to notice that syscache_info.h is installed into
$installdir/include/server/catalog if you use a non-VPATH
autoconf build, but not if you use a VPATH build or meson.
This is not great IMO.

Just to confuse matters even more, meson builds install a copy of
src/include/catalog/README, which autoconf builds do not.

ISTM we need to get these things in sync.

You could argue that syscache_info.h could never be useful outside the
core server, but it'd be a bit painful to get the non-VPATH code to
not install it, because it just blindly installs everything matching
src/include/catalog/*.h.  So I'd vote for making the other two paths
install it too.

I've not looked into why meson is installing a copy of that
README, but it seems quite random to do so, so I'd vote for
not doing that if possible.

Thoughts?

            regards, tom lane