simpleperf: gecko_profile_generator.py: Add --percpu-samples

It is to show sample distribution for each cpu:
1) Use cpu ids as thread names.
2) In each sample, add thread name + process name as the root
   of the call stack.

Bug: 323605908
Test: run test.py --only-host-test
Change-Id: Ie6e363727069876d8093bedd93c37daeb0a76cf0
1 file changed