Fixed Makefile dependenies for the args.h rule.
Fixed Makefile cases where echo with -n is used. On some systems,
/bin/sh does not use -n, so we must call /bin/echo -n instead
via the ${ECHON} Makefile variable.
Add missing standard tools to sub-Makefiles to make them
easier to invoke directly.
Sort lists of standard tool Makefile variables and remove duplicates.
Declare the SHELL at the top of Makefiles.
Fixed the depend rule in the custom Makefile.
