LeakSanitizer Cwd

[rurban]

When building with the clang-4.0 address-sanitizer this will error in global destruction:

most reliably with perl installperl. But also sometimes with

LSAN_OPTIONS=verbosity=1 ./perl -Ilib -I. -DD -MCwd -e'getcwd()'
==3620==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 200 byte(s) in 4 object(s) allocated from:
    #0 0x4fcab0  (cperl-5.27.0d-nt-asan/perl+0x4fcab0)
    #1 0x7f29dbf14e82  (/lib/x86_64-linux-gnu/libc.so.6+0xdbe82)

SUMMARY: AddressSanitizer: 200 byte(s) leaked in 4 allocation(s).

Check if we can bypass LSAN on our optree destruction bypass cheater

[rurban]

We cannot in the code, only with a link-time suppressor flag, linking to a blacklist file.