[MIPS] Use common definitions from asm-generic/signal.h

#define SIG_SETMASK32	256	/* Goodie from SGI for BSD compatibility:

				   set only the low 32 bit of the sigset.  */

/* Type of a signal handler.  */

typedef void __signalfn_t(int);

typedef __signalfn_t __user *__sighandler_t;

/* Fake signal functions */

#define SIG_DFL	((__sighandler_t)0)	/* default signal handling */

#define SIG_IGN	((__sighandler_t)1)	/* ignore signal */

#define SIG_ERR	((__sighandler_t)-1)	/* error return from signal */

#include <asm-generic/signal.h>

struct sigaction {

	unsigned int	sa_flags;