ANDROID: GKI: add fields from per-process mm event tracking feature

mm_event feature exports mm_event_count function and adds new fields
in the task_struct. Fix ABI diffs by adding the necessary padding.

Bug: 80168800
Bug: 116825053
Bug: 153442668
Test: boot
Change-Id: I4e69c994f47402766481c58ab5ec2071180964b8
Signed-off-by: Minchan Kim <minchan@google.com>
(cherry picked from commit 04ff5ec537a5f9f546dcb32257d8fbc1f4d9ca2d)
Signed-off-by: Martin Liu <liumartin@google.com>
[surenb: cherry picked and trimmed the original patch to include only
necessary changes to resolve ABI diff for task_struct and
mm_event_count, changed enum mm_event_type to contain the final
members]

Bug: 149182139
Test: build and boot
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: Iacdba61298ba15fc71b46e0323b4160f174300b7