s390/signal: cleanup uapi struct sigaction

#include <asm-generic/signal-defs.h>

#ifndef __KERNEL__

/* Here we must cater to libcs that poke about in kernel headers.  */

/*

 * There are two system calls in regard to sigaction, sys_rt_sigaction

 * and sys_sigaction. Internally the kernel uses the struct old_sigaction

 * for the older sys_sigaction system call, and the kernel version of the

 * struct sigaction for the newer sys_rt_sigaction.

 *

 * The uapi definition for struct sigaction has made a strange distinction

 * between 31-bit and 64-bit in the past. For 64-bit the uapi structure

 * looks like the kernel struct sigaction, but for 31-bit it used to

 * look like the kernel struct old_sigaction. That practically made the

 * structure unusable for either system call. To get around this problem

 * the glibc always had its own definitions for the sigaction structures.

 *

 * The current struct sigaction uapi definition below is suitable for the

 * sys_rt_sigaction system call only.

 */

struct sigaction {

        union {

          __sighandler_t _sa_handler;

          void (*_sa_sigaction)(int, struct siginfo *, void *);

        } _u;

#ifndef __s390x__ /* lovely */

        sigset_t sa_mask;

        unsigned long sa_flags;

        void (*sa_restorer)(void);

#else  /* __s390x__ */

        unsigned long sa_flags;

        void (*sa_restorer)(void);

	sigset_t sa_mask;

#endif /* __s390x__ */

};

#define sa_handler      _u._sa_handler