simpleperf: fix build_id checking.

Native libraries in apks may not have build ids. So change to below
rules when looking for a debug elf file:
1) If having a build id, the build ids should match.
2) Otherwise, the debug elf file should exist and not have a build id.

Bug: none
Test: run simpleperf_unit_test.
Test: test.py.
Change-Id: I01332e3010a6df17e70c6c55e15874d43bfaeb86
5 files changed