Fix #72409 - return previous handler

[bp1222]

This patch addresses https://bugs.php.net/bug.php?id=72409
It does alter default behavior in a potentially BC-incompatable
means. In the event someone was === true, the return value
of pcntl_signal(). However, this change could be applied to
master with small changes.

This patch is applied to master compared to PR #1952 which was
patching 5.6.x branch of PHP

[bishopb]

I'm not opposed to the BC break, but for consideration to address the breakage, a new function that returns the current handler assignment (\SIG_DFL, \SIG_IGN, or callable):

$oact = pcntl_signal_handler($signo);
pcntl_signal($signo, $nact);
// ... 
pcntl_signal($signo, $oact);

[trowski]

After some discussion, I think a better direction would be an additional function, pcntl_signal_get_handler().

@weltling Would it be acceptable to add this function to 7.0 as well?

[bp1222]

Should this function be in-addition-to, or instead of returning the old-act form pcntl_signal?

[trowski]

@bp1222 Instead of returning the old value from pcntl_signal(). That function should be unchanged.

[trowski]

@bp1222 Can you open a clean PR with just what's needed for the getter function? Then this can be merged.

[bp1222]

Will do. Closing this one now, will submit new in a bit.