[ct test] Explicitly unregister event receiver to avoid badarg

... when two tests are run within the same test case.
Fix if-clauses that make code to be unreachable

Fix two cases where use of assigment operator instead of comparison
operator causes if-clauses to be always false and code to be unreachable.
Make shell ctrl-u save killed text correctly

Fix edlin to correctly save text killed with ctrl-u. Prior to this fix,
entering text into the Erlang shell and then killing it with ctrl-u
followed by yanking it back with ctrl-y would result in the yanked text
being the reverse of the original killed text.

Add a test for the fix to interactive_shell_SUITE.

(This is the same fix as in PR#416, but that PR was never completed.)
httpc: Fix a typo in the documentation
ssl: Fix link error in documentation
Merge branch 's1n4/httpc_doc_typo' into maint

OTP-12221

* s1n4/httpc_doc_typo:
  httpc: Fix a typo in the documentation
Merge branch 'ia/ssl/link-fix' into maint

* ia/ssl/link-fix:
  ssl: Fix link error in documentation
Merge branch 'jjhoo/win32-fix-unreachable-code' into maint

OTP-12222

* jjhoo/win32-fix-unreachable-code:
  Fix if-clauses that make code to be unreachable
Merge branch 'vinoski/edlin-ctrl-u' into maint

OTP-12224

* vinoski/edlin-ctrl-u:
  Make shell ctrl-u save killed text correctly
dialyzer: fix bug concerning compiler option 'warnings_as_errors'

A typical scenario: the type digraph() is used in R16 (compilation
with the option 'warnings_as_errors' results in no warning); then the
module is analyzed by a 17 Dialyzer where digraph() is obsolete, and
since the warning is turned into an error Dialyzer fails to load the
module.

Thanks to Michael Truog.
dialyzer: Ignore ERL_COMPILER_OPTIONS when compiling

If, for instance, 'warn_unused_import' is present in
ERL_COMPILER_OPTIONS then many files in Erlang/OTP (Kernel, STDLIB,
...) cannot be analyzed by Dialyzer since the option is not present
when compiling Erlang/OTP, but 'warnings_as_errors' is.

The case that ERL_COMPILER_OPTIONS contains 'warnings_as_errors' can
only be handled by ignoring ERL_COMPILER_OPTIONS.
Merge branch 'siri/cuddle-with-tests' into maint

* siri/cuddle-with-tests:
  [ct test] Explicitly unregister event receiver to avoid badarg
dialyzer: do a minor re-factoring

A minor re-factoring and generalization.
ct: .gitignore ct_property_test.xml
Merge branch 'hans/update_gitignore' into maint

* hans/update_gitignore:
  ct: .gitignore ct_property_test.xml
Merge branch 'hb/dialyzer/warnings_as_errors/OTP-12225' into maint

* hb/dialyzer/warnings_as_errors/OTP-12225:
  dialyzer: do a minor re-factoring
  dialyzer: Ignore ERL_COMPILER_OPTIONS when compiling
  dialyzer: fix bug concerning compiler option 'warnings_as_errors'
[observer] Remove note about R15B nodes in user guide

A note in the user guide says "Only R15B nodes can be observed". This
note was written because the observer_backend module did not exist in
earlier releases. It should have said "R15B or later". However, now
that we are on OTP-17, we don't think the note is necessary anymore so
it is now removed.
Merge branch 'siri/observer/remove-doc-note/OTP-12078' into maint

* siri/observer/remove-doc-note/OTP-12078:
  [observer] Remove note about R15B nodes in user guide