pgsql: Ensure that all three build methods install the same set of file

Ensure that all three build methods install the same set of files.

syscache_info.h was installed into $installdir/include/server/catalog
if you use a non-VPATH autoconf build, but not if you use a VPATH
build or meson. That happened because the makefiles blindly install
src/include/catalog/*.h, and in a non-VPATH build the generated
header files would be swept up in that. While it's hard to conjure
a reason to need syscache_info.h outside of backend build, it's
also hard to get the makefiles to skip syscache_info.h, so let's
go the other way and install it in the other two cases too.

Another problem, new in v19, was that meson builds install a copy of
src/include/catalog/README, while autoconf builds do not. The issue
here is that that file is new and wasn't added to meson.build's
exclusion list.

While it's clearly a bug if different build methods don't install
the same set of files, I doubt anyone would thank us for changing
the behavior in released branches. Hence, fix in master only.

Author: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Reviewed-by: Andres Freund <andres(at)anarazel(dot)de>
Discussion: https://postgr.es/m/946828.1771185367@sss.pgh.pa.us

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/6be5b76d66cadbea715defa109963939ea866922

Modified Files
--------------
src/include/catalog/Makefile | 3 ++-
src/include/catalog/meson.build | 2 +-
src/include/meson.build | 1 +
3 files changed, 4 insertions(+), 2 deletions(-)