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/core.c

@@ -180,6 +180,7 @@ void
 ui_suspend(void)
 {
     inp_suspend();
+    doupdate();
     endwin();
 }
 
@@ -190,6 +191,22 @@ ui_resume(void)
     inp_resume();
 }
 
+void
+ui_beep(void)
+{
+    if (!isendwin()) {
+        beep();
+    }
+}
+
+void
+ui_flash(void)
+{
+    if (!isendwin()) {
+        flash();
+    }
+}
+
 void
 ui_resize(void)
 {