wasi_socket_ext.c: fix error reporting

do not return __WASI_ERRNO_xxx error code where 0/-1 is more appropriate.

most of them were not harmful because the value of
__WASI_ERRNO_SUCCESS is 0.

the one with __WASI_ERRNO_NOPROTOOPT in socket() is
a user-visible bug.

tested with wamr-wasi-extensions/samples/socket-tcp-udp.

cf. #4474

Author: yamt