clang-tidy: sync argument names in prototype and definition

Discovered with clang-tidy checker
`readability-inconsistent-declaration-parameter-name`.

Also:
- do not enforce the above because of inconsistencies still present
  between public API prototypes and definitions. (Also betwen man page
  protos, and man page examples, and other parts of the code, e.g.
  `easy` vs `curl` vs `d` vs `handle`) Perhaps subject for a future
  effort:
  https://github.com/curl/curl/actions/runs/22166472728/job/64094691653
- enable and fix `readability-named-parameter` where missing.

Refs:
https://clang.llvm.org/extra/clang-tidy/checks/readability/inconsistent-declaration-parameter-name.html
https://clang.llvm.org/extra/clang-tidy/checks/readability/named-parameter.html

Closes #20624

lib/select.h

@@ -71,7 +71,8 @@ struct pollfd {
    therefore defined here */
 #define CURL_CSELECT_IN2 (CURL_CSELECT_ERR << 1)
 
-int Curl_socket_check(curl_socket_t readfd, curl_socket_t readfd2,
+int Curl_socket_check(curl_socket_t readfd0,
+                      curl_socket_t readfd1,
                       curl_socket_t writefd,
                       timediff_t timeout_ms);
 #define SOCKET_READABLE(x, z)                               \