simpleperf: port read_apk and read_apk/read_elf tests to nonlinux.

Also make following small changes:
1. Manage testdata files like libziparchive.
2. Replace StringToPid() with android::base::ParseInt().
3. Add tests in read_elf_test.

Bug: 26962895

Change-Id: I6603e9f3cea3a013e2618ea003790d102739f843
16 files changed