libxml-namespacesupport: use stable v1.12 release; inherit ptest-perl

libxml-namespacesupport: use stable v1.12 release; inherit ptest-perl

* Fix RDEPENDS
* Upstream v1.12_9 is a development version, not a stable release
* Add UPSTREAM_CHECK_REGEX skip development releases
* Drop anonymous python function to "fix" version, which breaks
  auto-upgrade-helper (AUH)
* Use LICENSE file for checksum rather than ephemeral META.yml
* License remains the same

Fixes: [YOCTO #12581]
License-Update: use LICENSE file for checksum

Signed-off-by: Tim Orling <timothy.t.orling@linux.intel.com>