pgsql: Use named captures in Catalog::ParseHeader()

Use named captures in Catalog::ParseHeader()

Using at least perl 5.14 is required since 4c15327, meaning that it is
possible to use named captures and the %+ hash instead of having to
count parenthesis groups manually.

While on it, CATALOG is made more flexible in its handling of
whitespaces for parameter lists (see the addition of \s* in this
case). The generated postgres.bki remains exactly the same before and
after this commit.

Author: Dagfinn Ilmari Mannsåker
Reviewed-by: John Naylor
Discussion: https://postgr.es/m/[email protected]

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/23d8624fe52efff0e1c8a6e809d51671f9f549d6

Modified Files
--------------
src/backend/catalog/Catalog.pm | 85 +++++++++++++++++++++++++-----------------
1 file changed, 50 insertions(+), 35 deletions(-)