pgsql: Add a --dbname option to the pg_regress script, and use

Log Message:
-----------
Add a --dbname option to the pg_regress script, and use pl_regression
for testing PLs and contrib_regression for testing contrib, instead of
overwriting the core system's regression database as formerly done.
Andrew Dunstan

Modified Files:
--------------
pgsql/contrib:
contrib-global.mk (r1.8 -> r1.9)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/contrib-global.mk.diff?r1=1.8&r2=1.9)
pgsql/contrib/dblink/expected:
dblink.out (r1.13 -> r1.14)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/dblink/expected/dblink.out.diff?r1=1.13&r2=1.14)
pgsql/contrib/dblink/sql:
dblink.sql (r1.12 -> r1.13)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/dblink/sql/dblink.sql.diff?r1=1.12&r2=1.13)
pgsql/src:
Makefile.global.in (r1.213 -> r1.214)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/Makefile.global.in.diff?r1=1.213&r2=1.214)
pgsql/src/makefiles:
pgxs.mk (r1.3 -> r1.4)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/makefiles/pgxs.mk.diff?r1=1.3&r2=1.4)
pgsql/src/pl/plperl:
GNUmakefile (r1.19 -> r1.20)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plperl/GNUmakefile.diff?r1=1.19&r2=1.20)
pgsql/src/pl/plpython:
Makefile (r1.19 -> r1.20)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpython/Makefile.diff?r1=1.19&r2=1.20)
pgsql/src/pl/tcl:
Makefile (r1.45 -> r1.46)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/tcl/Makefile.diff?r1=1.45&r2=1.46)
pgsql/src/test/regress:
pg_regress.sh (r1.54 -> r1.55)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/pg_regress.sh.diff?r1=1.54&r2=1.55)