mu4e: restore support for function bookmarks

Fixes 2446.

mu4e/mu4e-bookmarks.el

@@ -53,11 +53,9 @@
 
 Each of the list elements is a plist with at least:
 `:name'  - the name of the query
-`:query' - the query expression string (not a function)
+`:query' - the query expression string or function
 `:key'   - the shortcut key (single character)
 
-Note that the :query parameter can be a function/lambda.
-
 Optionally, you can add the following:
 
 - `:favorite' - if t, monitor the results of this query, and make

mu4e/mu4e-search.el

@@ -203,6 +203,7 @@ the search."
          (or expr
              (mu4e-ask-bookmark
               (if edit "Select bookmark: " "Bookmark: "))))
+         (expr (if (functionp expr) (funcall expr) expr))
          (fav (mu4e--bookmark-query (mu4e-bookmark-favorite))))
     ;; reset baseline when searching for the favorite bookmark query
     (when (and fav (string= fav expr))