When a system had no interface, this function used xmalloc for root
but did not return any reference to it. This patch fixes it by
immediately returning an empty array if no interface is found.
Coverity Scan found this bug.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43121 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* ext/socket/extconf.rb: check for if_nametoindex() for
i686-w64-mingw32, and check for declarations of if_indextoname() and
if_nametoindex().
* ext/socket/ifaddr.c (ifaddr_ifindex): not-implement unless
if_nametoindex() is available.
* ext/socket/rubysocket.h: declare if_indextoname() and
if_nametoindex() if available but not declared.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40738 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
