2.122: changes requested by sds.
* use only one package for everything: ASDF. This simplifies the upgrade a bit. * export component-visited-p, record an index rather than a boolean. Also * On CLISP, only use custom:*module-provider-functions* when defined (2.49+) * In Makefile, mrproper before debian package. * Document that CLISP and SCL now support REQUIREing through ASDF. * Fix mistake in run-tests that made it always use sbcl