[DWARF] Store CFA value on DW_CFA_remember_state

Previously, CFA_remember_state stored only the register locations but ignored the CFA value. This needs also to be remembered and restored for correct behavior. The problem occurs, e.g., on functions with multiple epilogues, where the CFA value after the first epilogue is becomes wrong.

Reviewed By: #debug-info, MaskRay

Differential Revision: https://reviews.llvm.org/D140338