curl: control ipv6 support based on DISTRO feature

curl: control ipv6 support based on DISTRO feature

By default ipv6 is auto detected for native builds but disabled when
cross compiling.

This commit adds a PACKAGECONFIG option, unconditionally enabled for
native and nativesdk builds and controlled by the ipv6 DISTRO feature
for target builds.

(From OE-Core rev: f8377e96b353f8cf4a5812fa14c1c0405f769096)

Signed-off-by: Andre McCurdy <armccurdy@gmail.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>