Made ext-pcntl optional, as it was in v8.

[den1n]

On V8 ext-pcntl was optional with SignalRegistry::isSupported().

laravel-backup/src/Commands/BaseCommand.php

Lines 17 to 19 in ce99f8a

	if ($this->runningInConsole() && SignalRegistry::isSupported()) {
	$this->handlesSignals[] = SIGINT;
	}

Previous similar PRs:

#1352
#1481