Show PTRACE_EVENT_STOP correctly in debug output

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
diff --git a/strace.c b/strace.c
index ab971b5..f767831 100644
--- a/strace.c
+++ b/strace.c
@@ -2029,10 +2029,13 @@
 					[PTRACE_EVENT_VFORK_DONE] = "VFORK_DONE",
 					[PTRACE_EVENT_EXEC]  = "EXEC",
 					[PTRACE_EVENT_EXIT]  = "EXIT",
+					/* [PTRACE_EVENT_STOP (=128)] would make biggish array */
 				};
 				const char *e;
 				if (event < ARRAY_SIZE(event_names))
 					e = event_names[event];
+				else if (event == PTRACE_EVENT_STOP)
+					e = "STOP";
 				else {
 					sprintf(buf, "?? (%u)", event);
 					e = buf;