automake: import upstream fix for perl 5.26

Build broke as distributions now include Perl 5.26 and automake
triggered an "Unescaped left brace in regex" error.
Import upstream commit 13f00eb449 to fix that.

Signed-off-by: Daniel Golle <[email protected]>

tools/automake/patches/010-automake-port-to-Perl-5.22-and-later.patch

@@ -0,0 +1,30 @@
+From 13f00eb4493c217269b76614759e452d8302955e Mon Sep 17 00:00:00 2001
+From: Paul Eggert <[email protected]>
+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.
+---
+ bin/automake.in | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/bin/automake.in b/bin/automake.in
+index a3a0aa318..2c8f31e14 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;
+ }
+ 
+-- 
+2.13.1
+