Use dedicated minibuffer history for mairix-search

* lisp/net/mairix.el (mairix-search-history): New variable.
(mairix-search): Use it (bug#79926).

etc/NEWS

@@ -1748,6 +1748,11 @@ This contains the list of regular expressions used to match "Re:" and
 international variants of it when modifying the Subject field in
 replies.
 
+** mairix
+
+---
+*** 'mairix-search' now keeps its own minibuffer history.
+
 ** Imap
 
 ---

lisp/net/mairix.el

@@ -200,6 +200,8 @@ Currently there are `threads' and `flags'.")
 
 ;;;; Internal variables
 
+(defvar mairix-search-history nil
+  "Minibuffer history for `mairix-search'.")
 (defvar mairix-last-search nil)
 (defvar mairix-searches-changed nil)
 
@@ -334,7 +336,7 @@ If THREADS is non-nil, also display whole threads of found
 messages.  Results will be put into the default search file."
   (interactive
    (list
-    (read-string "Query: ")
+    (read-string "Query: " nil 'mairix-search-history)
     (y-or-n-p "Include threads? ")))
   (when (mairix-call-mairix
 	 (split-string search)