debuggerd_handler: add SIGSYS to the list of handled signals.

Bug: http://b/34586922
Test: kill -SYS $$
Change-Id: I31dadb9c65141d0c5556cc7256439e0a8d1519ab

debuggerd/include/debuggerd/handler.h

@@ -48,6 +48,7 @@ static void __attribute__((__unused__)) debuggerd_register_handlers(struct sigac
 #if defined(SIGSTKFLT)
   sigaction(SIGSTKFLT, action, nullptr);
 #endif
+  sigaction(SIGSYS, action, nullptr);
   sigaction(SIGTRAP, action, nullptr);
   sigaction(DEBUGGER_SIGNAL, action, nullptr);
 }