pgsql: Refactor PG_TEST_EXTRA logic in autoconf build

Refactor PG_TEST_EXTRA logic in autoconf build

To avoid duplicating the PG_TEST_EXTRA logic in Makefiles into the upcoming
meson based build definition, move the checks into the the tests
themselves. That also has the advantage of making skipped tests visible.

Reviewed-by: Peter Eisentraut 
Author: Nazir Bilal Yavuz 
Author: Andres Freund 
Discussion: https://postgr.es/m/7dae5979-c6c0-cec5-7a36-76a85aa8053d@enterprisedb.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/c3382a3c3ccda6df126c95bf37dcc762480c5202

Modified Files
--------------
src/test/Makefile               | 15 +++++----------
src/test/kerberos/t/001_auth.pl |  4 ++++
src/test/ldap/t/001_auth.pl     |  4 ++++
src/test/ssl/t/001_ssltests.pl  |  4 ++++
src/test/ssl/t/002_scram.pl     |  4 ++++
src/test/ssl/t/003_sslinfo.pl   |  4 ++++
6 files changed, 25 insertions(+), 10 deletions(-)