Bug #73783 raises an issue with signal handling when using SIG_IGN.
With PHP7.1 ZEND_SIGNALS is defaulted to on, which will for all
signals set the handler as zend_signal_handler_defer. This is
problematic for syscalls like sleep(), which will only return when the
requisite number of seconds have elapsed, or, a non-ignored signal is
raised. In this case we want to SIG_IGN SIGCHLD, however, SIG_IGN is
only stored in the SIGG(handlers) array, and the actual system level
handler is defined. This prevents proper signal ignoring when requeted.
This needs to go into 5.4 as well, but will wait for Pierre to review win32 situation
# Patch by Lucas Nealan, Arnaud Le Blanc, Brian Shire & Ilia Alshanetsky
