* maint-20:
  Updated OTP version
  Update release notes
  Update version numbers
  erts: Add system_flags(erts_alloc,"+M?sbct *")
  erts: Add age order first fit allocator strategies
  erts: Refactor erl_ao_firstfit_alloc
  erts: Add migration options "acnl" and "acfml"
  kernel: Add os:cmd/2 with max_size option
  erts: Add more stats for mbcs_pool
  erts: Fix alloc_SUITE:migration
  stdlib: Make ets_SUITE memory check try again
  erts: Improve carrier pool search
  erts: Improve alloc_SUITE:migration
  erts: Refactor carrier dealloc migration

into 'sverker/maint-20/alloc-n-migration/ERIERL-88'

OTP-14915
OTP-14916
OTP-14917
OTP-14918

The Design Principles states that an application can have Erlang
source files one level below the "src" directory, and now
filelib:find_source() by default searches one level below "src".

The same applies to "esrc". That directory is only mentioned in
filename(3).

as memory stats do not guarantee consistency.

A typical ETS test case ends by a lot of deallocating
that may now trigger homecoming carrier migration,
that in turn can cause quite large inconsistencies
in memory stats when same carrier is accounted for twice
or not at all.

And that's my theory why I now sometimes see transient discrepancies
between before and after memory stats.

Avoid unicode_util module call for ASCII strings

Exit early for Latin-1

When comparing the process dictionary before and after a test, only
(a sorted list of) qlc keys are compared.