Fix Utils.pm's locale-munging so that Perl itself is also affected.

Utils.pm has a BEGIN block that editorializes on the locale-related
environment variables, primarily in order to stabilize the behavior
of child programs.  It turns out that if the calling test script
has already done "use locale", this fails to affect the behavior
of Perl itself, causing locale behavior to be different between
Perl and child programs.  That breaks commit cd82e5c's attempt
to deal with locale-specific behavior in psql.

To fix, we just need to call setlocale() to redo the calculation
of locale.

Per report from Aleksander Alekseev.  No back-patch for now, since
there are no locale-dependent TAP tests in prior branches, and
I'm not yet convinced that this won't have side-effects of its own.

Discussion: https://postgr.es/m/CAJ7c6TO9KpYYxoVVseWEQB5KtjWDkt8NfyAeKPcHoe2Jq+ykpw@mail.gmail.com

Author: tglsfdc

src/test/perl/PostgreSQL/Test/Utils.pm

@@ -55,6 +55,7 @@ use File::Spec;
 use File::stat qw(stat);
 use File::Temp ();
 use IPC::Run;
+use POSIX qw(locale_h);
 use PostgreSQL::Test::SimpleTee;
 
 # We need a version of Test::More recent enough to support subtests
@@ -103,6 +104,7 @@ BEGIN
 	delete $ENV{LANGUAGE};
 	delete $ENV{LC_ALL};
 	$ENV{LC_MESSAGES} = 'C';
+	setlocale(LC_ALL, "");
 
 	# This list should be kept in sync with pg_regress.c.
 	my @envkeys = qw (