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

scripts/perlcheck.sh

@@ -25,8 +25,8 @@
 
 # The xargs invocation is portable, but does not preserve spaces in filenames.
 # If such a file is ever added, then this can be portably fixed by switching to
-# "xargs -I{}" and appending {} to the end of the xargs arguments (which will
-# call cmakelint once per file) or by using the GNU extension "xargs -d'\n'".
+# "xargs -I{}" and appending {} to the end of the xargs arguments (which calls
+# cmakelint once per file) or by using the GNU extension "xargs -d'\n'".
 
 set -eu