The problem is that we set a variable "docs_dir" based on whether or
not sgmltools is present (in configure.in), and then we do or do not
include docs in SUBDIRS in Makefile.am based on that.
So when I run "make dist" on a system, because I have not sgmltools,
it skips the docs directory.
So I'm going to try including docs in SUBDIRS all the time, but
passing down a variable for the all target in the docs/Makefile.am,
so its all target will be blank if sgmltools is missing.