simpleperf: fix according to unwindstack change.

unwindstack::Maps uses prev_real_map instead of prev_map, which
breaks simpleperf code building up prev_map links. So switch to
use unwindstack::Maps::Sort() to build up prev_real_map links.

Also add more tests.

Bug: 148075852
Test: run simpleperf_unit_test.
Change-Id: Ica0551e2d5a84aa8a0671489821fed1d263324f4
4 files changed