erts: Prevent valgrind from repeating same memory leaks reports

by using the macro VALGRIND_DO_ADDED_LEAK_CHECK if it exists
for system_info({error_checker,memory})
fixed small typo (missing right parenthesis) in gen_fsm example
Merge branch 'sverk/valgrind-added-leak-check' into maint

* sverk/valgrind-added-leak-check:
  erts: Prevent valgrind from repeating same memory leaks reports
add erl-xcom-arm-linux.conf
Merge branch 'henrik/xcomp-arm' into maint
[inets/httpd] Fixed mod_head handling of "new" response
[inets/httpd] Logging cleanup

Remove logging when fo keep-alive connection timeout. This is
a normal event (feature) not an error.
[inets/httpd] Improved access log entry

Sometimes the size of a response could be as a string.
[inets/httpd] Improved request handler terminate error-log entry

If a request handler terminates abnormally (terminate reason not
normal), the error-log entry was a bit obtuse ("Internal Server Error").
This has been improved so that the log entry now also include the
actual terminate reason.
erl_docgen: fix code highlighting and warning and note parts in erl_docgen
Merge branch 'fredrik/doc/syntax_highlight/OTP-11237' into maint

* fredrik/doc/syntax_highlight/OTP-11237:
  erl_docgen: fix code highlighting and warning and note parts in erl_docgen
Merge branch 'bsmr-erlang/fix_gen_fsm_example/OTP-11472' into maint

* bsmr-erlang/fix_gen_fsm_example/OTP-11472:
  fixed small typo (missing right parenthesis) in gen_fsm example
Merge branch 'bmk/inets/httpd/fix_mod_head_response/OTP-11328' into maint