Generate illegal instruction fault if LWS syscall returns -EFAULT.

2022-01-02  John David Anglin  <danglin@gcc.gnu.org>

libgcc/ChangeLog:

	* config/pa/linux-atomic.c (_ASM_EFAULT): Define.
	(__kernel_cmpxchg): Nullify illegal iitlbp instruction if error
	return is not equal _ASM_EFAULT.
	(__kernel_cmpxchg2): Likewise.