Ports: Add a cmake port

Yes, you build this *inside* serenity.

Ports/cmake/patches/0012-bin-bash.patch

@@ -0,0 +1,17 @@
+diff -urp a/bootstrap b/bootstrap
+--- a/bootstrap	2021-02-12 16:01:09.075367557 +0330
++++ b/bootstrap	2021-02-12 15:59:27.811749370 +0330
+@@ -1,4 +1,4 @@
+-#!/bin/sh
++#!/bin/bash
+ # Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+ # file Copyright.txt or https://cmake.org/licensing for details.
+ 
+diff -urp a/configure b/configure
+--- a/configure	2021-02-12 16:02:00.042148704 +0330
++++ b/configure	2021-02-12 16:02:07.035496388 +0330
+@@ -1,3 +1,3 @@
+-#!/bin/sh
++#!/bin/bash
+ cmake_source_dir=`cd "\`dirname \"$0\"\`";pwd`
+ exec "${cmake_source_dir}/bootstrap" "$@"