[test_server] Don't write unicode strings to latin1 log files

The unicode update of test_server for R16A introduced a few potential
errors when logging to files. Sometimes ~tp or ~ts was used for
formatting also when writing to files that were not opened with the
{encoding,utf8} option. If then the argument contained unicode
characters above 255, the file descriptor would crash. This has been
corrected by the following modifications:

* Since the 'unexpected_io' log file is used only when the test case
  HTML file is not available (e.g. between test cases), this file is
  now also a HTML file and as other test_server HTML logs it is always
  UTF-8 encoded

* Since it is possible to change which information is going to which
  log file (with test_server_ctrl:set_levels/3), we do not have full
  control over which information is written to which file. This means
  that any printout could be written to the 'major' log file
  (suite.log), which was earlier encoded as latin1. To avoid crashing
  this file descriptor due to unicode strings, the 'major' log file is
  now also encoded in UTF-8 (possible incopatibility).

* The cross_cover.info file is no longer a text file which can be read
  with file:consult/1, instead it is written as a pure binary file
  using term_to_binary when writing and binary_to_term when reading.

* The encoding of the file named 'last_name', which only content is
  the path to the last run.<timestamp> directory, is now dependent on
  the file name mode of the VM. If file names are expected to be
  unicode, then the 'last_name' file is UTF-8 encoded, else it is
  latin1 encoded.

Also, ~tp is changed back to ~p unless it is somehow likely that the
argument includes strings. It is not obvious that this is the correct
thing to do, but some decission had to be taken...
[test_server] Add error printouts in case writing to test case html log fails

Errors are printed to unexpected_io log.
test_server: Increase timeout for VALGRIND
Update config.guess and config.sub to latest versions
Repair broken force_stop functionality
Merge branch 'sverk/valgrind-cuddling'

* sverk/valgrind-cuddling:
  test_server: Increase timeout for VALGRIND
  erts: Use native atomics and fallback spinlock to mutex for VALGRIND
Merge remote branch 'origin/peppe/common_test/force_stop'

* origin/peppe/common_test/force_stop:
  Repair broken force_stop functionality

OTP-10832
Update copyright years
Prepare release