Microdumps: support aarch64 and lib mapping from APK

- Filter modules by prot flags (only +x) not extensions. It wouldn't
  otherwise catch the case of Chrome mapping the library from the
  apk (which is mapped r-x but doesn't end in .so).
- Use compile-time detection of target arch, in order to cope with
  multilib OSes, where uname() doesn't reflect the run-time arch.
- Add OS information and CPU arch / count.
- Add support for aarch64.
- Add tests and stackwalk expectations for aarch64.
- Fix a potential overflow bug in the processor.
- Rebaseline the tests using smaller symbols.
- Fix microdump_writer_unittest.cc on 32-bit host.

BUG=chromium:410294

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1407 4c0a9323-5329-0410-9bdc-e9ce6186880e
21 files changed