Makefiles.*: It should be possible to run 'make menuconfig' with no .config...

Makefiles.*: It should be possible to run 'make menuconfig' with no .config and no Make.defs file.  This change removes the dependency on Make.defs, but does not solve the problem of the missing .config file.  Without a .config file, it is not currently possible for the Makefile.* to correctly setup up the symbolic links to directories.