aarch64 SFrame: skip with warning new CFI directive used with pauth_lr

Today, SFrame v2 specification does not describe how to encode the
information corresponding to the PAuth_LR PAC signing method (it only
supports PAuth PAC signing method).
SFrame v3 specification should hopefully specify it.

In the meantime, if the GNU assembler finds .cfi_negate_ra_state_with_pc
and --gsframe is specified, it will output a warning to the user and
will fail to generate the FDE entry.

A new SFrame test for .cfi_negate_ra_state_with_pc is also added to
reflect this issue.

Approved-by: Indu Bhagat <indu.bhagat@oracle.com>