Don't implicitly dereference DW_CFA_def_cfa_expression.

The specification isn't entirely clear. Follow the gdb interpretation.

Bug: 73954823
Test: libunwindstack_test
Change-Id: If72717f54eed84e442f43af19e615143a9796b68
4 files changed
tree: 3c0059fcda80e98d96b344cc4e6c986ee5587b96
  1. libbacktrace/
  2. libunwindstack/