kconfig: add basic helper macros to scripts/Kconfig.include

Kconfig got text processing tools like we see in Make.  Add Kconfig
helper macros to scripts/Kconfig.include like we collect Makefile
macros in scripts/Kbuild.include.

Signed-off-by: Masahiro Yamada <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Reviewed-by: Ulf Magnusson <[email protected]>
4 files changed