simpleperf: accept different perf_attr sizes.

The size of perf_attr can be increased as new features are added. And
we can accept different perf_attr sizes in perf.data, and ignore
unknown features.

Bug: 26962895

Change-Id: Ia42617f92acb3ab6ae56eb91aa0d7b73efc0b8af
(cherry picked from commit dd2ae2878b7e5ac1754da55a08cbcdacadf53d78)
1 file changed