gnu: aerc: Enable building without zoxide.

* gnu/packages/mail.scm (aerc)[arguments]: Only substitute zoxide path
when it is an input.
[inputs]: Only add zoxide when building on a supported system.

Change-Id: I39b859982e1455e80a4b28979079c633e386fa34

gnu/packages/mail.scm

@@ -4915,11 +4915,12 @@ remote SMTP server.")
                         (string-append
                          "\"" (search-input-file inputs "bin/sh")
                          "\"")))
+                     (when (assoc-ref inputs "zoxide")
                        (substitute* "commands/z.go"
                          (("\"zoxide\"")
                           (string-append
                             "\"" (search-input-file inputs "bin/zoxide")
-                         "\"")))
+                            "\""))))
                      (substitute* (list "lib/crypto/gpg/gpg.go"
                                         "lib/crypto/gpg/gpg_test.go"
                                         "lib/crypto/gpg/gpgbin/keys.go"
@@ -4939,7 +4940,9 @@ remote SMTP server.")
                    (invoke "make" "CC=gcc" "install" "-C"
                            (string-append "src/" import-path)
                            (string-append "PREFIX=" #$output)))))))
-    (inputs (list gnupg
+    (inputs
+     (append
+       (list gnupg
              go-github-com-zenhack-go-notmuch
              go-golang-org-x-oauth2
              go-github-com-xo-terminfo
@@ -4976,8 +4979,10 @@ remote SMTP server.")
              go-git-sr-ht-sircmpwn-getopt
              go-git-sr-ht-rockorager-tcell-term
              python
-                  python-vobject
-                  zoxide))
+             python-vobject)
+       (if (supported-package? zoxide)
+           (list zoxide)
+           '())))
     (native-inputs (list scdoc))
     (home-page "https://git.sr.ht/~rjarry/aerc")
     (synopsis "Email client for the terminal")