UCS_to_most.pl: Process encodings in sorted order

Otherwise the order depends on the Perl hash implementation, making it
cumbersome to scan the output when debugging.

src/backend/utils/mb/Unicode/UCS_to_most.pl

@@ -50,7 +50,7 @@ my %filename = (
 	'GBK'        => 'CP936.TXT');
 
 # make maps for all encodings if not specified
-my @charsets = (scalar(@ARGV) > 0) ? @ARGV : keys(%filename);
+my @charsets = (scalar(@ARGV) > 0) ? @ARGV : sort keys(%filename);
 
 foreach my $charset (@charsets)
 {