[ 13724]
Fix for alarm() breaking into wait*().
Call PERL_ASYNC_CHECK() on EINTR in Perl_wait4pid(), to dispatch
signal handler before caller re-does the system call.
p4raw-link: @13724 on //depot/perlio:
cddd4526476ba0ae3c81876684c5e7a648cb3265
p4raw-id: //depot/perl@13725