net: declare lib_getaddrinfo as returning int32

net: declare lib_getaddrinfo as returning int32

    Otherwise on a 64-bit system we will read the 32-bit value as a 64-bit
    value.  Since getaddrinfo returns negative numbers as error values,
    these will be interpreted as numbers like 0xfffffffe rather than -2,
    and the comparisons with values like syscall.EAI_NONAME will fail.

    Fixes golang/go#23645

    Reviewed-on: https://go-review.googlesource.com/91296

From-SVN: r257299