Makefile(s): Hook kconfig into build system

This still needs work but the basic idea works with a example
src/Kconfig to elaborate on later, once the remaining issues with the
Makefiles have been solved.

Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Makefile.rules: Add toolchain Makefiles and some minor fixes

Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Make is silent per default, but 'make V=1' will show all compiler calls

Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Makefile.rules: Collect .PHONY terms together

Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Makefile.{rules}: Improve ifeq/ifneq syntax

Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
clang: pragma diagnostic pop without push

"error: pragma diagnostic pop could not pop, no matching push"

Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>