Change 'ensure-directories-exist' to look for 'mkdir' in $PATH, not in /bin.

--- maxima-5.36.1/lisp-utils/defsystem.lisp.orig	2014-11-22 16:21:30.000000000 -0500
+++ maxima-5.36.1/lisp-utils/defsystem.lisp	2015-05-25 21:53:31.223648483 -0400
@@ -4627,7 +4627,7 @@
         (cmd (if (member :win32 *features*)
                  (format nil "mkdir \"~a\""
                          (coerce (subst #\\ #\/ (coerce (namestring dir) 'list)) 'string))
-                 (format nil "/bin/mkdir -p ~S" (namestring dir)))))
+                 (format nil "mkdir -p ~S" (namestring dir)))))
    (unless (directory dir)
      (lisp:system cmd))
    ;; The second return value is supposed to be T if directories were
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<tr><td><span title='2020-06-05 22:54:06 +0200'>2020-06-05</span></td><td><a href='/guix/commit/tests/ed25519bis.key?id=c83eedba2361c3831d3efb5ad63d5077d636fb28'>git-authenticate: Add tests.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>