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/unit/unit1666.c

@@ -35,7 +35,7 @@ struct test_1666 {
   CURLcode result_exp;
 };
 
-/* the size of the object needs to deduct the null terminator */
+/* the size of the object needs to deduct the null-terminator */
 #define OID(x) x, sizeof(x) - 1
 
 static bool test1666(const struct test_1666 *spec, size_t i,

tests/unit/unit1667.c

@@ -66,7 +66,7 @@ static bool test1667(const struct test_1667 *spec, size_t i,
   }
   else if(!result) {
     /* use strlen on the pointer instead of curlx_dyn_len() because for some
-       of these type, the code explicitly adds a null terminator which is then
+       of these type, the code explicitly adds a null-terminator which is then
        counted as buffer size. */
     size_t actual_len = strlen(curlx_dyn_ptr(dbuf));
     if(strlen(spec->out) != actual_len) {