[PATCH] emacs: avoid warning about notmuch-show-get-message-id

[Daniel Kahn Gillmor]

Without this change, we see the following warning when compiling the
elisp:

```
EMACS emacs/notmuch-crypto.elc

In end of data:
emacs/notmuch-crypto.el:266:1:Warning: the function
    ‘notmuch-show-get-message-id’ is not known to be defined.
```

Thanks to Örjan Ekeberg and David Edmondson for their followup about
this.

Signed-off-by: Daniel Kahn Gillmor <dkg at fifthhorseman.net>
---
 emacs/notmuch-crypto.el | 1 +
 1 file changed, 1 insertion(+)

diff --git a/emacs/notmuch-crypto.el b/emacs/notmuch-crypto.el
index 4035ee37..928de0bb 100644
--- a/emacs/notmuch-crypto.el
+++ b/emacs/notmuch-crypto.el
@@ -163,6 +163,7 @@ by user FROM."
       (recenter -1))))
 
 (declare-function notmuch-show-refresh-view "notmuch-show" (&optional reset-state))
+(declare-function notmuch-show-get-message-id "notmuch-show" (&optional bare))
 
 (defun notmuch-crypto--async-key-sentinel (process event)
   "When the user asks for a GPG key to be retrieved
-- 
2.25.1