tidy-up: miscellaneous

- INSTALL-CMAKE.md: add missing periods, text fixes.
- md4, md5: sync variables names.
- curl_trc: sync an argument type.
- docs/examples: sync debug/trace function copies, constify, tidy-ups.
- replace commented code with `#if 0`.
- drop redundant parenthesis (macro values, `return`, around single
  variables, function calls).
- fix indentation, apply clang-format in places.

Closes #20481

CMakeLists.txt

@@ -1746,7 +1746,7 @@ if(NOT WIN32 AND NOT CMAKE_CROSSCOMPILING)
     {
       (void)argc;
       argv[0][0] = ' ';
-      return (argv[0][0] == ' ')?0:1;
+      return (argv[0][0] == ' ') ? 0 : 1;
     }" HAVE_WRITABLE_ARGV)
 endif()