Change the subtag used for maps from 0xB to 0xF

The subtag chosen for maps breaks crucial assumptions in other parts of
the system, in particular the native code generation scheme used in the
HiPE compiler. Therefore it is better to use 'the other' unused subtag.

The main change here is the use of 0xF subtag for maps instead of 0xB.
The rest of the differences are changes to and additions of comments.

One more comment from my part.
I noticed that the file contains the following two lines:

The comment of the second line is most certainly a copy and paste error
and should be appropriately fixed by the OTP developers. More importantly,
it would be great if that subtag (0x7) turned out to be unused and could
be used for maps instead of the 0xF one. This might turn out very handy
in the future. I can elaborate on this, if needed.
Merge branch 'lukas/ose/master-17.0/OTP-11334'

* lukas/ose/master-17.0/OTP-11334:
  ose: Fix erts assert failed printouts
  ose: fix for packet_bytes in fd/spawn driver.
  ose: Prepare slave for running on OSE
  ose: Fix bug when hunting for signal proxy
  ose: Implement tcp inet driver for OSE
  ose: Add ifdefs for HAVE_UDP
  ose: Yielding has to be done differently for background processes.
  ose: Print faults in aio sys driver calls
  ose: Prinout errno when to_erl read fails
  ose: erlang display goes to ramlog printf
  ose: Initiate stdin/stdout/stderr
  ose: Break lmconf into one per load module
  ose: Reset busy port when pdq empty
  ose: Restore the owner of the signal
Document an escript:create/2 hidden feature

escript:create/2 accepts a 3-elements tuple containing files and
zip:create/3 options to build a zip file.

Also had to update zip typespecs to allow referral from escript docs.
Merge branch 'pf/document-escript-feature-only-present-in-examples/OTP-11827'

* pf/document-escript-feature-only-present-in-examples/OTP-11827:
  Document an escript:create/2 hidden feature
Merge branch 'matwey/systemd/OTP-11829'

* matwey/systemd/OTP-11829:
  Add systemd socket activation for epmd.

Conflicts:
	erts/epmd/src/epmd_int.h

Extra ticket: OTP-11828
inets: Avoid Windows XP port problems
inets: Avoid timing issus in test case code
Merge branch 'hans/ssh/login_hangs/OTP-11823'
Merge branch 'siri/cdv-bugs/OTP-11650'

* siri/cdv-bugs/OTP-11650:
  Improve crashdump_viewer_SUITE:start_stop test case
  Fix crash in crashdump_viewer when node has multiple creations
  Change spawn/1 + monitor/2 to spawn_monitor/1 to avoid deadlock
Fix problem with bad match error after close
Relax time limits for parallel groups tests
erts: Adjust is_external_header() for new map tag

to not mistake a map for an external term (pid, port or ref).
stdlib: Fix map type listing
doc: Document Maps datatype in reference manual
erts: Fix bug of scheduling a suspended process

This is a race that can cause RUNNING (instead of RUNNING_SYS)
set on a SUSPENDED process. The effect of this race happening is probably
quite benign.

The bug was discovered by process_SUITE:processes_gc_trap on debug VM
crashing on last assert in schedule():

/* Never run a suspended process */
ASSERT(!(ERTS_PSFLG_SUSPENDED & erts_smp_atomic32_read_nob(&p->state)));
erts: Fix bug in test case port_SUITE:otp_5119
wx: loosen testcase
stdlib: loosen testcases

Stabilize tests for all kind of machines

Old sparc (and newer smaller) machines timeouts in 'random_ref_comp'
decrease load and increase timeouts.

Supervisor:
Turn up accepted time, since if non-linear it should be much worse,
now the test failes on slow multicore machines

Remove memory tests, they fail sometimes and those tests are not
needed to be tested. Hard to predict GC's and other processes behaviours.
mnesia: Dialyzer fixes
mnesia: test harder sync