Stabilize output of new regression test.

Per buildfarm, the output order of \dx+ isn't consistent across
locales.  Apply NO_LOCALE to force C locale.  There might be a
more localized way, but I'm not seeing it offhand, and anyway
there is nothing in this test module that particularly cares
about locales.

Security: CVE-2022-2625

src/test/modules/test_extensions/Makefile

@@ -17,6 +17,9 @@ DATA = test_ext1--1.0.sql test_ext2--1.0.sql test_ext3--1.0.sql \
 
 REGRESS = test_extensions test_extdepend
 
+# force C locale for output stability
+NO_LOCALE = 1
+
 ifdef USE_PGXS
 PG_CONFIG = pg_config
 PGXS := $(shell $(PG_CONFIG) --pgxs)