Add patch to remove "use encoding" which is gone in perl 5.26.

Closes: #866934

debian/patches/series

 fix-pod-errors.patch
 network-tests.patch
 spelling.patch
+use-encoding.patch

debian/patches/use-encoding.patch

+Description: 'use encoding' is gone in perl 5.26
+ Simply remove it for now; the code is ascii anyway, and
+ if the output needs utf-8, other solutions can be found.
+Origin: vendor
+Bug-Debian: https://bugs.debian.org/866934
+Author: gregor herrmann <gregoa@debian.org>
+Last-Update: 2017-07-15
+Forwarded: https://github.com/LibreCat/perl-oai-lib/pull/2
+Bug: https://github.com/LibreCat/perl-oai-lib/pull/2
+
+--- a/bin/oai_pmh.pl
++++ b/bin/oai_pmh.pl
+@@ -1,7 +1,5 @@
+ #!/usr/bin/perl
+ 
+-use encoding 'utf8';
+-
+ use HTTP::OAI;
+ use Getopt::Long;
+ use Pod::Usage;