* 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

into 'sverker/maint-19/alloc-n-migration/ERIERL-88'

to change sbct limit in runtime for chosen allocator type.

With great power comes great responsibility.

similar to the ones in OTP-19.2.3.1

1.2.11 started bailing when avail_out==0 regardless of whether
there's anything to flush or not, and there's no point in adapting
the old method since it was vulnerable to bugs in other zlib
versions which updated the deflate parameters even on failure.

The api_deflateParams test has been expanded accordingly, and two
white-box cases in zip_usage has been updated to make fewer
assumptions about the output; the validity of the compressed data
is what matters, not whether it's exactly the same as the test
vector.

I accidentally merged a few fixes directly to maint-20 (and then to maint
and master), instead of merging to maint and master and waiting for a
patch to merge it into maint-20, leaving the related tickets dangling.

This commit does nothing beyond getting the tickets (and their release
notes) into the next patch.

Quoting RFC 1952:

"A gzip file consists of a series of "members" (compressed data
sets). [...] The members simply appear one after another in the
file, with no additional information before, between, or after
them."