chore(3p/lisp): import mime4cl source tarball

Used http://wcp.sdf-eu.org/software/mime4cl-20150207T211851.tbz (sha256
5a914669bba7561efe59a4fd0817204c07ad2add98b03ae206ef185ac04affb3).
Importing seems sensible since there's no upstream repo nor has their
been a release since 2015.

This is just an import commit, so the changes made to make it build are
more discoverable as their own commit.

Change-Id: I2ff28c3c7433abdf7857204bc89eaf9edc0b1cbc
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3378
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>

third_party/lisp/mime4cl/test/mime.lisp

@@ -0,0 +1,53 @@
+ ;;; mime.lisp --- MIME regression tests
+
+ ;;; Copyright (C) 2012 by Walter C. Pelissero
+
+ ;;; Author: Walter C. Pelissero <walter@pelissero.de>
+ ;;; Project: mime4cl
+
+#+cmu (ext:file-comment "$Module: mime.lisp")
+
+;;; This library is free software; you can redistribute it and/or
+;;; modify it under the terms of the GNU Lesser General Public License
+;;; as published by the Free Software Foundation; either version 2.1
+;;; of the License, or (at your option) any later version.
+;;; This library is distributed in the hope that it will be useful,
+;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; Lesser General Public License for more details.
+;;; You should have received a copy of the GNU Lesser General Public
+;;; License along with this library; if not, write to the Free
+;;; Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+;;; 02111-1307 USA
+
+(in-package :mime4cl-tests)
+
+(defvar *samples-directory*
+  (merge-pathnames (make-pathname :directory '(:relative "samples"))
+		   #.(or *compile-file-pathname*
+			 *load-pathname*
+			 #P"")))
+
+(deftest mime.1
+    (let* ((orig (mime-message (make-pathname :defaults #.(or *compile-file-pathname*
+							   *load-pathname*)
+					   :name "sample1"
+					   :type "msg")))
+	   (dup (mime-message (with-output-to-string (out) (encode-mime-part orig out)))))
+      (mime= orig dup))
+  t)
+
+(deftest mime.2
+    (loop
+       for f in (directory (make-pathname :defaults *samples-directory*
+					  :name :wild
+					  :type "txt"))
+       do
+	 (format t "~A:~%" f)
+	 (finish-output)
+	 (let* ((orig (mime-message f))
+		(dup (mime-message (with-output-to-string (out) (encode-mime-part orig out)))))
+	   (unless (mime= orig dup)
+	     (return nil)))
+       finally (return t))
+  t)