Include config/local/$file in config/$file where it makes sense and
create empty local configs during build if not present.

Modified-by: Michael Brown <mcb30@etherboot.org>
Signed-off-by: Michael Brown <mcb30@etherboot.org>

Tested with COM1 and COM2.

Signed-off-by: Michael Brown <mcb30@etherboot.org>

Add FILE_LICENCE declarations to almost all files that make up the
various standard builds of gPXE.