Fork issues with 3.4 in Docker only

[Christoph Reiter]

After the upgrade to 3.4 (disclaimer: in MSYS2) I'm seeing, and getting reports
of, various things failing in Docker only, for example:

      1 [main] pacman 252 child_copy: dll data read copy failed,
0x7FF8C816C000..0x7FF8C8178EB0, done 0, windows pid 5096, Win32 error
299
      0 [main] pacman 251 dofork: child -1 - forked process 5096 died
unexpectedly, retry 0, exit code 0xC0000005, errno 11
      0 [main] pacman 253 child_copy: dll data read copy failed,
0x7FF8C816C000..0x7FF8C8178EB0, done 0, windows pid 584, Win32 error
299
  67887 [main] pacman 251 dofork: child -1 - forked process 584 died
unexpectedly, retry 0, exit code 0xC0000005, errno 11
      0 [main] pacman 254 child_copy: dll data read copy failed,
0x7FF8C816C000..0x7FF8C8178EB0, done 0, windows pid 2336, Win32 error
299
 124719 [main] pacman 251 dofork: child -1 - forked process 2336 died
unexpectedly, retry 0, exit code 0xC0000005, errno 11

Reverting https://cygwin.com/git/?p=newlib-cygwin.git;a=commit;h=943433b00cacdde0cb9507d0178770a2fb67bd71
fixes things again.

Note that this doesn't happen outside of Docker, I've built more than 100
packages with 3.4 on different hosts without any issues, and the errors in
Docker are pretty consistent, so I'm guessing that something with ASLR behaves
differently under Docker(?)

Note that I haven't had time to look into reproducing it with cygwin
itself. I can try to do that if needed.

thanks