Fix a really dumb bug introduced in version 1.4 of this file (a patch for ipv6

Fix a really dumb bug introduced in version 1.4 of this file (a patch for ipv6
support) which could cause things like EOF and read errors while reading
/etc/services to always return a TRY_AGAIN.  The perl test suite would alloc a
larger buffer and try again until all memory was exhausted.  When we get a read
error, or EOF, it means we didn't get what we wanted, and so we should return
an error.  Doing so fixes the failing perl 5.8.2 test.
 -Erik