intltool: add patch to fix compatibility with Perl 5.26

intltool: add patch to fix compatibility with Perl 5.26

When Perl 5.26 is installed on the host, building some packages like
avahi fail, because of intltool-update:

```
Unescaped left brace in regex is illegal here in regex; marked by <-- HERE in m/^(.*)\${ <-- HERE ?([A-Z_]+)}?(.*)$/ at $BUILDROOT/host/usr/bin/intltool-update line 1065.
```

Apparently, this has been a warning before Perl 5.26, but now it is an
error.

Fetch from:
https://github.com/Alexpux/MSYS2-packages/blob/master/intltool/perl-5.22-compatibility.patch

Reported upstream:
https://bugs.launchpad.net/intltool/+bug/1696658

Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>