Test/V07pcre.ztst

This test uses

if ! zmodload zsh/pcre
...

to decide whether to run the test.  I just encountered a case where
the zmodload succeeded in loading zsh/pcre from an older installed
version of zsh, so the test executed but failed, even though
--enable-pcre was not configured.

I'm not sure how that happened because ztst.zsh should be resetting
module_path and I'm not getting other failures on module tests?