Update autoconf-archive sub-module
The autoconf-archive sub-module needs to be updated to
v2019.01.06, but the existing list of m4 macros has grown a very long list of dependencies, which in turn have recursive dependencies on other m4 macros.
Just updating the sub-module broke the build — see #2 (closed). Any update will need to track down the list of dependencies, recursively, and figure out how to add them.