meson: Add two missing regress tests

It's likely worth adding some automated way of preventing further
omissions. We're discussing how to best do that.

Reported-by: Justin Pryzby <pryzby@telsasoft.com>
Discussion: https://postgr.es/m/20230117173509.GV9837@telsasoft.com

contrib/pg_stat_statements/meson.build

@@ -41,6 +41,7 @@ tests += {
   'regress': {
     'sql': [
       'pg_stat_statements',
+      'oldextversions',
     ],
     'regress_args': ['--temp-config', files('pg_stat_statements.conf')],
     # Disabled because these tests require

src/test/modules/unsafe_tests/meson.build

@@ -8,6 +8,7 @@ tests += {
     'sql': [
       'rolenames',
       'alter_system_table',
+      'guc_privs',
     ],
   },
 }