[ipv6] RFR: 8223532: Don't try creating IPv4 sockets in NetworkInterface.c if IPv4 is not supported

[Alan Bateman]

On 08/05/2019 12:51, Chris Hegarty wrote:
>
> While the vast majority of libnet.so is devoted to socket related
> implementation, not all is. There are a small number of low-level pieces
> of functionality that can be used with support for either IPv4 or IPv6
> being present. The NIO implementation also uses some shared common
> functionality from libnet.so. It seems overly restricting to disallow
> libnet.so from loading if neither IPv4 or IPv6 are present.
>
I agree as an innocent reference to a type in java.net might resulting 
in libnet being loaded as a side effect. We also have the issue that the 
file system implementation is in libnio so libnet will be loaded there 
too (although shouldn't trigger its JNI OnLoad to be run).

-Alan