* tests/aclocal6.test: New file.

* tests/aclocal6.test: New file.
* lib/am/configure.am (am--refresh): New rule.
(%MAKEFILE-IN%, %MAKEFILE%, $(top_builddir)/config.status,
$(top_srcdir)/configure): Call the top-level am--refresh from
subdirectories.
($(ACLOCAL_M4)): Depend upon %CONFIGURE_DEPS%.  Call the
top-level am--refresh when not in the top-level directory.
Fix jump directories for VPATH builds.
Suggested by Raja R. Harinath.