browser: make M-W/M-Q functional right after startup, if there is history

Do the same what the normal "research" code does: if nothing was
searched for yet during this session, and there is a history of
search items, then search for the last item in that history.

src/browser.c

@@ -725,6 +725,12 @@ void do_filesearch(bool forwards)
  * either forwards or backwards. */
 void do_fileresearch(bool forwards)
 {
+#ifdef ENABLE_HISTORIES
+	/* If nothing was searched for yet, take the last item from history. */
+	if (*last_search == '\0' && searchbot->prev != NULL)
+		last_search = mallocstrcpy(last_search, searchbot->prev->data);
+#endif
+
 	if (*last_search == '\0')
 		statusbar(_("No current search pattern"));
 	else