Integrate perlio:

[ 10597]
Check that HVs with HvNAME() != NULL are really stashes before
treating them as such. Also be more defensive on the GvCV.
Win32 fork and dprof now working again.

[ 10595]
Skip Perl_my_bcopy in .def file as we do not provide it.
- Win32 (VC++) now builds but fails:
filefind.t - suspect Win32's builtin cwd is not doing insecure dir test
fork.t     - No &___ENV_HV_NAME___::CLONE method ???
write.t    - open(...,"|-") not implemented on Win32

p4raw-link: @10597 on //depot/perlio: 5f438a9a23e13957a6f27a6c29850d4dce382023
p4raw-link: @10595 on //depot/perlio: 9d50d3997b5daf2ecaed7d0cafc86ab4121491bc

p4raw-id: //depot/perl@10598