gnu-tar: patch configure, don't autoreconf

Testing patching configure to see if we can avoid the autoreconf.

In Tigerbrew (mistydemeo/tigerbrew#221) I ran into an issue where adding the extra dependencies caused an unsatisfiable tap dependency. (gnu-tar is a dependency of git, autoconf/automake became dependencies of gnu-tar, and autoconf/automake need a newer m4 from homebrew/dupes - which can't be tapped without git.)