* Replace AM_PROG_MKDIR_P with AC_PROG_MKDIR_P. AM_PROG_MKDIR_P has
been deprecated and may be removed in a future version of automake.
AC_PROG_MKDIR_P is available in autoconf 2.60 and later, and we
currently require at least 2.61.
* Use AC_LANG_SOURCE for the code passed to AC_{RUN,LINK}_IFELSE.
* Pass the subdir-objects option to AM_INIT_AUTOMAKE to create objects in
sub-directories.
* Try harder to find the asciidoc icons directory that contains the
images we need to build the new users' guide.
* Don't invoke a2x with --destination-dir when generating manpages.