simpleperf: fix unknown binary in samples.

1. Wrong ip addresses in callchain can map to unknown binary. They
  should be omitted.
2. When unknown binary is really hitted in samples, which is unlikely
  to happen, make sure report-sample cmd will not skip the file id of
  unknown binary.
3. Add corresponding test.

Bug: http://b/37783312
Test: run simpleperf_unit_test.
Change-Id: Ifb5b59401bce9c8f81042015e73f190acd43ce31
7 files changed