[BUG]: xemacs build fails if EMACSLOADPATH defined

If a user has defined EMACSLOADPATH while building XEmacs, then the bootstrapping mechanism fails. This could happen, for example, if a user is building XEmacs in a shell running an older version of XEmacs. The failure occurs even if EMACSLOADPATH is defined to be the same value as EMACSBOOTSTRAPLOADPATH. As an additional note, we really should have `not' available as a primitive in Lisp code all the time. Patch in separate message. Nevertheless the problem reported here should be fixed. src $ make dump-elcs # This one works EMACSBOOTSTRAPLOADPATH="/home/martin/x/dev/src/../lisp/:/home/martin/x/build/mde" ./temacs -batch -l /home/martin/x/dev/src/../lisp/update-elc.el Loading /home/martin/x/dev/src/../lisp/update-elc.el... Loading find-paths.el... (14096) Loading packages.el... (22488) Loading setup-paths.el... (5408) Loading dump-paths.el... (0) Loading /home/martin/x/build/mde/src/../lisp/dumped-lisp.el... (52) Loading /home/martin/x/packages/lisp/Sun/dumped-lisp.el... (28) Loading /home/martin/x/packages/lisp/ediff/dumped-lisp.el... (0) Loading /home/martin/x/packages/lisp/efs/dumped-lisp.el... (0) Loading /home/martin/x/packages/lisp/tooltalk/dumped-lisp.el... (28) Loading /home/martin/x/packages/lisp/vc/dumped-lisp.el... (0) Loading /home/martin/x/packages/lisp/vm/dumped-lisp.el... (0) Loading /home/martin/x/mule-packages/lisp/egg-its/dumped-lisp.el... (20) Loading /home/martin/x/mule-packages/lisp/skk/dumped-lisp.el... (0) src $ EMACSLOADPATH=/foo make dump-elcs # This one fails EMACSBOOTSTRAPLOADPATH="/home/martin/x/dev/src/../lisp/:/home/martin/x/build/mde" ./temacs -batch -l /home/martin/x/dev/src/../lisp/update-elc.el Loading /home/martin/x/dev/src/../lisp/update-elc.el... Loading find-paths.el... (14096) Loading packages.el... (22488) Loading setup-paths.el... (5408) Loading dump-paths.el... Symbol's function definition is void : not # The next one also fails, even with EMACSLOADPATH=EMACSBOOTSTRAPLOADPATH src $ EMACSLOADPATH="/home/martin/x/dev/src/../lisp/:/home/martin/x/build/mde" make dump-elcs EMACSBOOTSTRAPLOADPATH="/home/martin/x/dev/src/../lisp/:/home/martin/x/build/mde" ./temacs -batch -l /home/martin/x/dev/src/../lisp/update-elc.el Loading /home/martin/x/dev/src/../lisp/update-elc.el... Loading find-paths.el... (14096) Loading packages.el... (22488) Loading setup-paths.el... (5408) Loading dump-paths.el... Symbol's function definition is void : not