Linux/x86: Update cancel_jmp_buf to match __jmp_buf_tag [BZ #22563]

Linux/x86: Update cancel_jmp_buf to match __jmp_buf_tag [BZ #22563]

On x86, padding in struct __jmp_buf_tag is used for shadow stack pointer
to support shadow stack in Intel Control-flow Enforcemen Technology.
Since the cancel_jmp_buf array is passed to setjmp and longjmp by
casting it to pointer to struct __jmp_buf_tag, it should be as large
as struct __jmp_buf_tag.  Otherwise when shadow stack is enabled,
setjmp and longjmp will write and read beyond cancel_jmp_buf when saving
and restoring shadow stack pointer.

This patch adds bits/types/__cancel_jmp_buf_tag.h to define struct
__cancel_jmp_buf_tag so that Linux/x86 can add saved_mask to
cancel_jmp_buf.

Tested natively on i386, x86_64 and x32.  Tested hppa-linux-gnu with
build-many-glibcs.py.

	[BZ #22563]
	* bits/types/__cancel_jmp_buf_tag.h: New file.
	* sysdeps/unix/sysv/linux/x86/bits/types/__cancel_jmp_buf_tag.h
	* sysdeps/unix/sysv/linux/x86/pthreaddef.h: Likewise.
	* sysdeps/unix/sysv/linux/x86/nptl/pthreadP.h: Likewise.
	* nptl/Makefile (headers): Add
	bits/types/__cancel_jmp_buf_tag.h.
	* nptl/descr.h [NEED_SAVED_MASK_IN_CANCEL_JMP_BUF]
	(pthread_unwind_buf): Add saved_mask to cancel_jmp_buf.
	* sysdeps/nptl/pthread.h: Include
	<bits/types/__cancel_jmp_buf_tag.h>.
	(__pthread_unwind_buf_t): Use struct __cancel_jmp_buf_tag with
	__cancel_jmp_buf.
	* sysdeps/unix/sysv/linux/hppa/pthread.h: Likewise.