fix(ui): guard terminal writes while suspended

We forgot to guard `beep()` and `flush()`.

Ref: 36ec2b0ae1
Ref: dd76f9087f
Signed-off-by: Michael Vetter <jubalh@iodoru.org>
Fixes: https://github.com/profanity-im/profanity/issues/2162
(cherry picked from commit 5e4b5d313a9e055e039e2feb4efae58b6aaead78)

src/ui/inputwin.c

@@ -459,7 +459,9 @@ _inp_write(char* line, int offset)
     _inp_win_handle_scroll();
 
     _inp_win_update_virtual();
-    doupdate();
+    if (!isendwin()) {
+        doupdate();
+    }
 }
 
 static int