Adds mcrypt extension for PHP 5.6.40

[nickkadutskyi]

Adds missing mcrypt ext from php-src.

[nickkadutskyi]

Fixes this issue #337

[jtojnar]

Also when ready, please combine the changes into a single commit titled php56.extensions.mcrypt: init

[nickkadutskyi]

Also when ready, please combine the changes into a single commit titled php56.extensions.mcrypt: init

Just force-pushed the squash

[jtojnar]

Looks like it also needs a check definition

nix-phps/checks.nix

Lines 32 to 36 in d40b1a1

	mysql = {
	description = "Build MySQL extension";
	enabled = { php, lib, ... }: lib.versionOlder php.version "7";
	drv = { php, ... }: php.extensions.mysql;
	};

[nickkadutskyi]

Looks like it also needs a check definition

nix-phps/checks.nix

Lines 32 to 36 in d40b1a1

	mysql = {
	description = "Build MySQL extension";
	enabled = { php, lib, ... }: lib.versionOlder php.version "7";
	drv = { php, ... }: php.extensions.mysql;
	};

Just add mcrypt into checks.

[jtojnar]

Thanks.