[RISCV] Do not outline CFI instructions when they are needed in EH

We saw a failure caused by unwinding with incomplete CFIs, so we
can't outline CFI instructions when they are needed in EH.

This is a recommit of 0d406889, which was reverted in ce838836 as
related precommit test 360d44e8 caused some errors.

Reviewed By: luismarques

Differential Revision: https://reviews.llvm.org/D122634