This update for postgresql16 fixes the following issues:

PostgreSQL upgrade to version 16.3 (bsc#1224051):

- CVE-2024-4317: Fixed visibility restriction of pg_stats_ext and pg_stats_ext_exprs entries to the table owner (bsc#1224038).

Bug fixes:

- Fix incompatibility with LLVM 18.
- Prepare for PostgreSQL 17.
- Make sure all compilation and doc generation happens in %build.
- Require LLVM <= 17 for now, because LLVM 18 doesn't seem to work.
- Remove constraints file because improved memory usage for s390x
- Use %patch -P N instead of deprecated %patchN.

Release notes:

- https://www.postgresql.org/docs/release/16.3/