automake: fix unescaped left brace warning patch

Automake currently has a unescaped left brace in it's automake.in folder
that generates the warning:
"Unescaped left brace in regex is deprecated, passed through in regex;"
This patch, which is backported from upstream fixes this warning.

Signed-off-by: Adam Duskett <aduskett@codeblue.com>
[Thomas: format patch using "git format-patch".]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/automake/0002-port-to-perl-5.22-and-later.patch

@@ -0,0 +1,34 @@
+From 13f00eb4493c217269b76614759e452d8302955e Mon Sep 17 00:00:00 2001
+From: Paul Eggert <eggert@cs.ucla.edu>
+Date: Thu, 31 Mar 2016 16:35:29 -0700
+Subject: [PATCH] automake: port to Perl 5.22 and later
+
+Without this change, Perl 5.22 complains "Unescaped left brace in
+regex is deprecated" and this is planned to become a hard error in
+Perl 5.26.  See:
+http://search.cpan.org/dist/perl-5.22.0/pod/perldelta.pod#A_literal_%22{%22_should_now_be_escaped_in_a_pattern
+* bin/automake.in (substitute_ac_subst_variables): Escape left brace.
+
+[Backported from:
+ http://git.savannah.gnu.org/cgit/automake.git/commit/?id=13f00eb4493c217269b76614759e452d8302955e]
+Signed-off-by: Adam Duskett <aduskett@gmail.com>
+---
+ bin/automake.in | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/bin/automake.in b/bin/automake.in
+index a3a0aa3..2c8f31e 100644
+--- a/bin/automake.in
++++ b/bin/automake.in
+@@ -3878,7 +3878,7 @@ sub substitute_ac_subst_variables_worker
+ sub substitute_ac_subst_variables
+ {
+   my ($text) = @_;
+-  $text =~ s/\${([^ \t=:+{}]+)}/substitute_ac_subst_variables_worker ($1)/ge;
++  $text =~ s/\$[{]([^ \t=:+{}]+)}/substitute_ac_subst_variables_worker ($1)/ge;
+   return $text;
+ }
+ 
+-- 
+2.7.4
+