get_maintainer: Fix --help warning

Using --help emits a concatenation error.  Fix it.
Signed-off-by: Joe Perches <joe@perches.com>
Reported-by: Paul Bolle <pebolle@tiscali.nl>
Tested-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/get_maintainer.pl

@@ -83,6 +83,8 @@ push(@signature_tags, "Signed-off-by:");
 push(@signature_tags, "Reviewed-by:");
 push(@signature_tags, "Acked-by:");
 
+my $signature_pattern = "\(" . join("|", @signature_tags) . "\)";
+
 # rfc822 email address - preloaded methods go here.
 my $rfc822_lwsp = "(?:(?:\\r\\n)?[ \\t])";
 my $rfc822_char = '[\\000-\\377]';
@@ -473,7 +475,6 @@ my @subsystem = ();
 my @status = ();
 my %deduplicate_name_hash = ();
 my %deduplicate_address_hash = ();
-my $signature_pattern;
 
 my @maintainers = get_maintainers();