Provided an implementation for gai_strerror and gave getaddrinfo sensibl...

Provided an implementation for gai_strerror and gave getaddrinfo sensible default behaviour when hints is set to NULL. Ideally getaddrinfo should supply multiple addrinfo values when hints is NULL or ai_family is set to AF_UNSPEC but this is a somewhat more complex proposition"
[fix-getaddrinfo-null-hints ea7053a] Provided an implementation for gai_strerror and gave getaddrinfo sensible default behaviour when hints is set to NULL. Ideally getaddrinfo should supply multiple addrinfo values when hints is NULL or ai_family is set to AF_UNSPEC but thas would be a somewhat more complex proposition.

test_getaddrinfo.c has been updated with a number of tests for hints = NULL and also for gai_strerror, running
./runner.py sockets.test_getaddrinfo

completes correctly.