tidy-up: miscellaneous

- avoid "will" in builds scripts, scripts folder, curl_easy_ssls_export.md,
  and few other files.
- badwords: add "initialise", "nul terminated", "thread safety" and
  variations.
- prefer "null-terminat", where missing (two places).
- fix "null-terminat*" missing dash.
- hostip: merge two `#if` blocks.
- tool_doswin: fix comment
  Spotted by GitHub Code Quality
  Follow-up to 9a2663322c #17572
- fix stray spaces and newlines.

Closes #21638

tests/sshserver.pl

@@ -1186,7 +1186,7 @@ if($sshdid =~ /OpenSSH-Windows/) {
     # Put an "exec" in front of the command so that the child process
     # keeps this child's process ID by being tied to the spawned shell.
     exec("exec $cmd") || die "Cannot exec() $cmd: $!";
-    # exec() will create a new process, but ties the existence of the
+    # exec() creates a new process, but ties the existence of the
     # new process to the parent waiting perl.exe and sh.exe processes.
 
     # exec() should never return back here to this process. We protect