op.h: Correct PERL_LOADMOD_IMPORT_OPS comment

This description, added in ec6d81aba, is misleading.
t/uni/parser.t: Make a test more robust

It was checking that *tèst returns a true value, which is somewhat
redundant.  I think ‘is’ was meant, rather than ‘ok’, considering what
was the test name (*main::tèst).
make_ext.pl: Typo in error message