Use __libc_ptf_call in _longjmp_unwind

Use __libc_ptf_call in _longjmp_unwind

Use __libc_ptf_call in _longjmp_unwind to avoid duplicated logic.  On
x86-64, I got

jmp-unwind.os:
_longjmp_unwind:
	movl	__libc_pthread_functions_init(%rip), %eax
	testl	%eax, %eax
	jne	.L4
	rep ret
.L4:
	movq	304+__libc_pthread_functions(%rip), %rax
	movq	%rsp, %rsi
	ror $2*8+1, %rax
	xor %fs:48, %rax
	jmp	*%rax

jmp-unwind.o:

_longjmp_unwind:
	movl	$__pthread_cleanup_upto, %eax
	testq	%rax, %rax
	je	.L1
	movq	%rsp, %rsi
	jmp	__pthread_cleanup_upto
.L1:
	rep ret

	* sysdeps/nptl/jmp-unwind.c: Include <libc-lock.h> instead of
	<nptl/pthreadP.h>.
	(_longjmp_unwind): Use __libc_ptf_call.
	* sysdeps/unix/sysv/linux/s390/jmp-unwind.c: Likewise.