[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
Merge branch 'siri/cuddle-with-tests' into maint

* siri/cuddle-with-tests:
  [ct test] Explicitly unregister event receiver to avoid badarg
ct: .gitignore ct_property_test.xml
Merge branch 'hans/update_gitignore' into maint

* hans/update_gitignore:
  ct: .gitignore ct_property_test.xml