Revert "Build and test Perl bindings out-of-tree."

There seems to be no sane way to build/test an
ExtUtils::MakeMaker-based project in a separate directory and get
identical results.

This reverts commit 887466794a40f57b84ce32524e1a650d6674c7e6.
Revert "perl: Ignore run-perl-tests (generated script)."

This reverts commit 72e2abf312358c228889cfff2f6ac10e9f61c5b5.