include: merge uv_tcp_bind and uv_tcp_bind6

Merge uv_tcp_bind6() into uv_tcp_bind().  uv_tcp_bind() now takes a
const struct sockaddr*.
include: merge uv_tcp_connect and uv_tcp_connect6

Merge uv_tcp_connect6() into uv_tcp_connect().  uv_tcp_connect() now
takes a const struct sockaddr*.
include: merge uv_udp_bind and uv_udp_bind6

Merge uv_udp_bind6() into uv_udp_bind().  uv_udp_bind() now takes a
const struct sockaddr*.
include: merge uv_udp_send and uv_udp_send6

Merge uv_udp_send6() into uv_udp_send().  uv_udp_send() now takes a
const struct sockaddr*.