llvm-symbolizer: Support loclist in FRAME.

Summary:
Support location lists in FRAME command.
These are used for the majority of local variables in optimized code.
Also support DW_OP_breg in addition to DW_OP_fbreg when it refers to the
same register as DW_AT_frame_base.

Reviewers: pcc, jdoerfert

Subscribers: srhines, hiraditya, rupprecht, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D70629