Change from v6:
- change CONFIG_BINDER_TRANSACTION_LATENCY_TRACKING type from bool to tristate
- add comments to @timestamp and @tv under struct binder_transaction
- make binder_txn_latency threshold configurable
- enhance lock protection
Change from v5:
- change config name to the proper one,
CONFIG_BINDER_TRANSACTION_LATENCY_TRACKING.
- change tracepoint name to more descriptive one,
trace_binder_txn_latency_(alloc|info|free)
- enhance some lock protection.
Change from v4:
- split up into patch series.
Change from v3:
- use tracepoints for binder_update_info and print_binder_transaction_ext,
instead of custom registration functions.
Change from v2:
- create transaction latency module to monitor slow transaction.
Change from v1:
- first patchset.
