osx: pass const handle pointer to uv___stream_fd

uv___stream_fd does not modify passed parameter, so non-const
pointer is not required here.
unix, windows: pass const handle ptr to uv_tcp_get*name

uv_tcp_getsockname and uv_tcp_getpeername do not modify passed handle
pointer, so there is no need to keep this parameter non-const.
common: pass const sockaddr ptr to uv_ip*_name

uv_ip4_name and uv_ip6_name do not modify passed sockaddr pointer,
so there is no need to keep this parameter non-const.