Integrate perlio:

[ 10048]
If wait() or waitpid() ends due to EINTR despatch perl interrupt handler
and re-try. Fixes "perl 5.7.x prefers suicide over killing more than one child."

p4raw-link: @10048 on //depot/perlio: 0a0ada86d5873275d2ecec5cb3ffc5cb284ca30d

p4raw-id: //depot/perl@10049