Seen to happen when run under WINE v10.0 on macOS.
```
$ CURL_TEST_EXE_EXT_SRV=.exe CURL_TEST_EXE_EXT_TOOL=.exe \
CURL_TEST_EXE_RUNNER=wine TFLAGS='951 -t' ninja tests
[...]
16:02:18.607002 [select_ws_wait_thread] PeekNamedPipe error: (0x00000032) - Request not supported.
[...endless repeat...]
```
Closes #20478
curlx_winapi_strerror(ret, buffer, sizeof(buffer));
logmsg("[select_ws_wait_thread] PeekNamedPipe error: (0x%08lx) - %s",
ret, buffer);
+ if(ret == ERROR_NOT_SUPPORTED) /* avoid potential endless loop */
+ break;
SleepEx(0, FALSE);
continue;
}