Orderfile: Simple call-graph-based orderfile.

This CL adds simple function call graph clustering. The call graph is
inferred from the function ordering offset list, and the orderfile is
produced by clustering based on this inferred call graph.

In local testing, this change recovers the speedometer performance
lost in the bug. Startup is not affected, and memory shows similar
improvement to the original system_health orderfile.

Bug: 894827
Change-Id: Iedab652d0f25c9c9ea481c2a75214cac41dee368
Reviewed-on: https://chromium-review.googlesource.com/c/1350876
Commit-Queue: Matthew Cary <mattcary@chromium.org>
Reviewed-by: Benoit L <lizeb@chromium.org>
Reviewed-by: Egor Pasko <pasko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612644}

• tools/cygprofile/cluster.py[Added - diff]
• tools/cygprofile/cluster_unittest.py[Added - diff]
• tools/cygprofile/orderfile_generator_backend.py[diff]
• tools/cygprofile/phased_orderfile.py[Deleted - diff]
• tools/cygprofile/phased_orderfile_unittest.py[Deleted - diff]
• tools/cygprofile/process_profiles.py[diff]
• tools/cygprofile/process_profiles_unittest.py[diff]
• tools/cygprofile/profile_android_startup.py[diff]