By default `pg_config --bindir` is executed during configure phase to
get the bin directory containing all the postgres executables used by
glom.
This seems wrong given that the same postgresql_15 package will be
executed on build and on the final host platform which is not
necessarily the same. To avoid that, specify the bin dir manually via
the corresponding configure option.
As described in the release lifecycle docs from postgresql[1], v11 will
stop receiving fixes as of Nov 9 2023. This means it's EOL throughout
the entire lifetime of 23.11, so let's drop it now.
A lot of examples are also referencing postgresql_11. Where it's
sensible, use postgresql_15 as example now to avoid confusion.
This is also handy because the LLVM 16 fix for postgresql is not
available for postgresql 11 ;-)
[1] https://www.postgresql.org/support/versioning/
