core: stop redefining E* macros on Windows, map EACCES, related fixes

Before this patch, standard `E*` errno codes were redefined on Windows,
onto matching winsock2 `WSA*` error codes, which have different values.
This broke uses where using the `E*` value in non-socket context, or
other places expecting a POSIX `errno`, e.g. file I/O, threads, IDN or
interfacing with dependencies.

Fix it by introducing a curl-specific `SOCKE*` set of macros that map to
`WSA*` on Windows and standard POSIX codes on other platforms. Then
verify and update the code to use `SOCKE*` or `E*` macro depending on
context.

- Add `SOCKE*` macros that map to either winsock2 or POSIX error codes.
  And use them with `SOCKERRNO` or in contexts requiring
  platform-dependent socket error codes.

  This fixes `E*` uses which were supposed be POSIX values, not `WSA*`
  socket errors, on Windows:
  - lib/curl_multibyte.c
  - lib/curl_threads.c
  - lib/idn.c
  - lib/vtls/gtls.c
  - lib/vtls/rustls.c
  - src/tool_cb_wrt.c
  - src/tool_dirhie.c

- Ban `E*` codes having a `SOCKE*` mapping, via checksrc.
  Authored-by: Daniel Stenberg

- Add exceptions for `E*` codes used in file I/O, or other contexts
  requiring POSIX error codes.

Also:
- ftp: fix missing `SOCKEACCES` mapping for Windows.
- add `SOCKENOMEM` for `Curl_getaddrinfo()` via `asyn-thread.c`.
- tests/server/sockfilt: fix to set `SOCKERRNO` in local `select()`
  override on Windows.
- lib/inet_ntop: fix to return `WSAEINVAL` on Windows, where `ENOSPC` is
  used on other platforms. To simulate Windows' built-in `inet_ntop()`,
  as tested on a Win10 machine.
  Note:
  - WINE returns `STATUS_INVALID_PARAMETER` = `0xC000000D`.
  - Microsoft documentation says it returns `WSA_INVALID_PARAMETER`
    (= `ERROR_INVALID_PARAMETER`) 87:
    https://learn.microsoft.com/windows/win32/api/ws2tcpip/nf-ws2tcpip-inet_ntop#return-value
- lib/inet_ntop: drop redundant `CURL_SETERRNO(ENOSPC)`.
  `inet_ntop4()` already sets it before returning `NULL`.
- replace stray `WSAEWOULDBLOCK` with `USE_WINSOCK` macro to detect
  winsock2.
- move existing `SOCKE*` mappings from `tests/server` to
  `curl_setup_once.h`.
- add missing `EINTR`, `EINVAL` constants for WinCE.

Follow-up to abf80aae38 #16612
Follow-up to d69425ed7d #16615
Bug: https://github.com/curl/curl/pull/16553#issuecomment-2704679377

Closes #16621

lib/curl_threads.c

@@ -127,6 +127,7 @@ curl_thread_t Curl_thread_create(
   if((t == 0) || (t == LongToHandle(-1L))) {
 #ifdef UNDER_CE
     DWORD gle = GetLastError();
+    /* !checksrc! disable ERRNOVAR 1 */
     int err = (gle == ERROR_ACCESS_DENIED ||
                gle == ERROR_NOT_ENOUGH_MEMORY) ?
                EACCES : EINVAL;