pgsql: Teach RPM the package name provided in Perl alias packages.

Teach RPM the package name provided in Perl alias packages.

When commit 1185be355462d1dc7e2950a7e52eb7ca0cb6f3c8 introduced
installation of a file containing "use PostgreSQL::Test::Utils", the RPM
Package Manager said "nothing provides perl(PostgreSQL::Test::Utils)".
Discussed on pgsql-packagers. Back-patch to v12, v13, and v14 only;
newer versions don't have the alias packages.

Reviewed by Andrew Dunstan, Tom Lane, and John Harvey. Reported by John
Harvey.

Branch
------
REL_12_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/646b16bcafeaa98d7a085ccf4bef11dfc0999fb8

Modified Files
--------------
src/test/perl/PostgreSQL/Test/Cluster.pm | 6 ++++++
src/test/perl/PostgreSQL/Test/Utils.pm | 6 ++++++
2 files changed, 12 insertions(+)