Same as this error:
https://www.redhat.com/archives/libguestfs/2011-April/msg00042.html
https://www.redhat.com/archives/libguestfs/2011-May/msg00041.html
We don't know why latest libtool is so obviously broken, but this
works around the problem.
+# Work around broken libtool.
+export to_tool_file_cmd=func_convert_file_noop
+
SUBDIRS = gnulib/lib generator lib images gnulib/tests sh xml po
if HAVE_OCAML
SUBDIRS = gnulib/lib generator lib images gnulib/tests sh xml po
if HAVE_OCAML