tests: Limit number of failed test cases in the curses output

It was possible for the scr.addstr() operations to fail and terminate
parallel-vm.py if the number of failed test cases increased beyond what
fits on the screen.

Signed-off-by: Jouni Malinen <j@w1.fi>

tests/hwsim/vm/parallel-vm.py

@@ -211,7 +211,13 @@ def show_progress(scr):
                 scr.move(num_servers + 2, 0)
                 scr.clrtoeol()
                 scr.addstr("Failed test cases: ")
+                count = 0
                 for f in failed:
+                    count += 1
+                    if count > 30:
+                        scr.addstr('...')
+                        scr.clrtoeol()
+                        break
                     scr.addstr(f)
                     scr.addstr(' ')