TODO t/c_argv.t test 2, ...

Changes: better wording
t/test.pl threw uninitialised ENV warnings on cygwin
TODO module.t DateTime <5.10
C: skip 5.10.1thr  $op->precomp assertions with wrong ops

fixes all failing perl5.10.1d module tests,
rm outdated log.modules-5.018001 (=> 5.18.2)
update more passing module tests