1. Performance: prefer posix_spawn when available (it has provide up to x100 boost on macOS arm64). It's a matter of extending what Prefer posix_spawn on OSX #126063 did by adding || defined(TARGET_MACCATALYST) here:

- #if defined(TARGET_OSX)
+ #if defined(TARGET_OSX) || defined(TARGET_MACCATALYST)

2. Perform IsTerminal check for MacCatalyst:

We never performed the extra configuration on these platforms:

For IsiOSLike platforms:

We were including:

That was a nop:

The fix will be to stop treating MacCatalyst as iOSLike in the project file:

and extend pal_log.m (context) with sth like:

int32_t SystemNative_IsATty(intptr_t fd)
{
#if defined(TARGET_MACCATALYST)
    return isatty(ToFileDescriptor(fd));
#elif defined(TARGET_IOS) || defined(TARGET_TVOS)
    // there is no terminal on these platforms
    (void)fd;
    return 0;
#endif
}

We need to get #126306 merged first and ensure all the MacCatalyst and iOS builds and tests are green.