Revert "Simulate Module::Install $(PERL) changing."

This reverts commit 1e0d49b8c19fd0ca142b41b8a445d30b93e46679.
(On e.g. Perl 5.10.1 adding -Mstrict to xsubpp causes problems)
Add compat-test for Module::Install behaviour to t/basic.t
Merge pull request #161 from mohawk2/removestricttest

Remove -Mstrict from t/xs.t