The ancient GPL (copied from the 2.6.12 kernel) build infrastructure is actually in the "kconfig" directory, not under scripts. Remind me to write a new one from scratch...
(Someone actually submitted a basic kconfig rewrite in awk once, but until I
bite the bullet and write my own awk.c, I just don't know awk well enough to
maintain a large script written in it. Back when I maintained kernel.org/doc
I wrote http://landley.net/hg/kdocs/file/tip/make/menuconfig2html.py but
I am NOT reintroducing python as a build dependency. And neither actually
implemented actual menuing part. So... todo list.)