Parallel make testsuite fixes.

Parallel make testsuite fixes.

* tests/configure-iface.at (installable libltdl)
(--with-ltdl-include/lib, --with-included-ltdl): Add dlopened
libmodule.la to main_DEPENDENCIES.
* tests/old-m4-iface.at (AC_WITH_LTDL): Likewise, let ltdldemo
depend upon module.la and libltdl/libltdlc.la.
* tests/testsuite.at (LT_AT_MAKE): Invoke each target in turn,
default to 'all'.
* tests/early-libtool.at (config.lt): Define 'all' target.

Signed-off-by: Ralf Wildenhues <Ralf.Wildenhues@gmx.de>