Handle possible race condition with `mkdir`

[arogachev]

https://github.com/kalessil/phpinspectionsea/blob/master/docs/probable-bugs.md#mkdir-race-condition

Extracted from comment:

rbac-php/src/CommonStorage.php

Lines 48 to 62 in cb61807

	if (!is_dir($directory)) {
	set_error_handler(static function (int $errorNumber, string $errorString) use ($directory): bool {
	// Handle race condition.
	// See https://github.com/kalessil/phpinspectionsea/blob/master/docs/probable-bugs.md#mkdir-race-condition
	if (!is_dir($directory)) {
	throw new RuntimeException(
	sprintf('Failed to create directory "%s". ', $directory) . $errorString,
	$errorNumber
	);
	}
	return true;
	});
	mkdir($directory, 0775, true);
	restore_error_handler();
	}