* sysdeps/mips/bits/wordsize.h: New file, appropriate for all

* sysdeps/mips/bits/wordsize.h: New file, appropriate for all
3 ABIs.
* sysdeps/mips/mips64/gmp-mparam.h: New file.  Define
BITS_PER_LONGINT to __WORDSIZE, to match all 3 ABIs.
* sysdeps/mips/setjmp_aux.c (STRINGXP, REGS, PTRS): New macros.
(__sigsetjmp_aux): Use them.  Adjust for all 3 ABIs.
* sysdeps/mips/elf/start.S: Adjust for all 3 ABIs.
* sysdeps/unix/mips/brk.S: Likewise.
* sysdeps/unix/mips/sysdep.S: Likewise.
* sysdeps/unix/sysv/linux/mips/clone.S: Likewise.
* sysdeps/mips/bits/setjmp.h (__jmp_buf): Likewise.
* sysdeps/mips/sys/ucontext.h: Likewise.
* sysdeps/unix/sysv/linux/mips/sys/profcs.h: Likewise.
* sysdeps/unix/sysv/linux/mips/sys/ucontext.h: Likewise.
* sysdeps/unix/sysv/linux/mips/kernel_stat.h: Likewise.
* sysdeps/mips/mips64/bsd-_setjmp.S: Likewise.
* sysdeps/mips/mips64/bsd-setjmp.S: Likewise.
* sysdeps/mips/mips64/setjmp.S: Likewise.
* sysdeps/mips/mips64/bits/setjmp.h: Deleted, obsolete.
* sysdeps/mips/mips64/soft-fp/sfp-machine.h: Use long long for
64-bit types.