Re-license PerconaFT 'locktree' to Apache V2

Follow up work to PS-4849 to re-license more of the locktree for RocksDB:

List #1
ft/comparator.h - OK, introduced with locktree
portability/toku_atomic.h - OK, introduced by [email protected] in 2012
portability/toku_instrumentation.h - OK, introduced by [email protected] in 2017
portability/toku_portability.h - OK, introduced by [email protected] in 2008
portability/toku_pthread.h - OK, introduced by [email protected] in 2008
portability/toku_race_tools.h - OK, introduced by [email protected] in 2012
util/dbt.h - OK, This one was extremely difficult to ID. It encapsulates a "DBT" or "Data Base Thing". This comes originally from BDB API. There is nothing that I can find that is specific to adding functionality to or around this in the various wrappers over the years that goes back to original MIT code.
util/dbt.cc - OK, This one was extremely difficult to ID. It encapsulates a "DBT" or "Data Base Thing". This comes originally from BDB API. There is nothing that I can find that is specific to adding functionality to or around this in the various wrappers over the years that goes back to original MIT code.
util/memarena.h - OK, introduced by [email protected] in 2008
util/memarena.cc - OK, introduced by [email protected] in 2008

List #2
ft/ft-status.h - (depends on util/status.h and util/partitioned_counter.*, see below) - OK, Introduced by [email protected] during status refactoring
util/status.h - (depends on util/partitioned_counter.*, see below) - OK, Introduced by [email protected] in 2013 as a part of a cleanup/refactor
portability/memory.h - OK, Introduced by [email protected] in 2007
portability/toku_time.h - OK, Introduced by [email protected] in 2008

Extras
util/partitioned_counter.* - Introduced by [email protected] in 2012. Files moved several times in their history, but all within Tokutek.