do_signal(): support for SIGSYS

as of POSIX.1-2001:
Signal  Value       Action  Comment
---------------------------------------------------
SIGSYS  12,31,12    Core    Bad argument to routine

arch/x86/kernel/syscall.c

@@ -412,6 +412,7 @@ do_signal(unsigned long rc, void *regs0, struct process *proc, struct sig_pendin
 		case SIGFPE:
 		case SIGSEGV:
 		case SIGBUS:
+		case SIGSYS:
 		core:
 			dkprintf("do_signal,default,core,sig=%d\n", sig);
 			coredump(proc, regs);