patch to fix gnu "make check" failures when perl-5.22 is in use

[Friedrich Haubensak]

perl v5.22 introduced the following (taken from perldelta.pod):
===
A literal C<"{"> should now be escaped in a pattern

If you want a literal left curly bracket (also called a left brace)
in a regular expression pattern, you should now escape it by either
preceding it with a backslash (C<"\{">) or enclosing it within square
brackets C<"[{]">, or by using C<\Q>; otherwise a deprecation warning
will be raised.  This was first announced as forthcoming in the v5.16
release; it will allow future extensions to the language to happen.
===

this affects the script build-aux/update-copyright of gnulib and,
when that is used in test-update-copyright.sh, results in failure of
"make check" in, e.g., diffutils-3.3, findutils-4.5.14, grep-2.21, a. o.,
as is already reported by bruce dubbs in bug-gnulib/2015-06/msg00024.html.

please apply the following patch to build-aux/update-copyright:

--- a/build-aux/update-copyright        2015-07-02 09:46:59.152942323 +0200
+++ b/build-aux/update-copyright        2015-07-02 09:49:21.306051099 +0200
@@ -124,7 +124,7 @@
 use warnings;

 my $copyright_re = 'Copyright';
-my $circle_c_re = '(?:\([cC]\)|@copyright{}|\\\\\(co|&copy;)';
+my $circle_c_re = '(?:\([cC]\)|@copyright\{}|\\\\\(co|&copy;)';
 my $holder = $ENV{UPDATE_COPYRIGHT_HOLDER};
 $holder ||= 'Free Software Foundation, Inc.';
 my $prefix_max = 5;

thank you, kind regards,
fritz