Fix miniupnpc setsockopt incompatible pointer type on Windows with GCC 14+

[skypher]

Summary

GCC 14+ treats -Wincompatible-pointer-types as an error by default. On Windows, setsockopt() expects const char* for the option value, and socket timeouts (SO_RCVTIMEO/SO_SNDTIMEO) use DWORD (milliseconds) instead of struct timeval.

This PR fixes the miniupnpc connecthostport.c to use the correct types on Windows:

• Use DWORD instead of struct timeval for the timeout variable
• Cast to (const char *) when calling setsockopt()
• Use milliseconds (3000) instead of seconds for the timeout value

Note: This was a latent bug

The original code was actually broken on Windows, not just a type mismatch. The code passed a struct timeval (8 bytes: {tv_sec=3, tv_usec=0}) but Windows expects a DWORD (4 bytes) containing milliseconds.

Windows would read only the first 4 bytes (value 3) as 3 milliseconds instead of the intended 3 seconds. The code appeared to work because connections usually succeeded before the tiny 3ms timeout kicked in, and older GCC versions only warned about the pointer type mismatch rather than erroring.

Test plan

• [x] Verified fix compiles with MinGW GCC 15.2.0 cross-compile for Windows
• [x] Full downstream project (devilutionx) Windows build completes successfully

[CLAassistant]

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[skypher]

The fix has already been merged in upstream miniupnp:

https://github.com/miniupnp/miniupnp/pull/866