Makefile.include: add rules to generate preprocessed versions of C files, or assembly code, for any file

This was used by platform CC2530DK which has been removed.

Previously, the CC2538 port would compile USB-related files from their original location under the CC2531 CPU dir. We are now removing the latter, but we need to keep those files.

Users should be adding such things to their local .git/info/exclude.

Those were relevant to platform/win32

Harmonise platform configuration

This does not seem to be needed anywhere or to achieve anything

We only have one rest engine now, the example does not need to try and configure this