'make distcheck' checks for out-of-source-tree builds and whether
the distribution tarball includes all source files. This commit
fixes many problems, except some remaining with src/test still
to-be-fixd.
This might need a lot of cleanup for out-of-source-tree builds and the
like, but let's not spend time on this now. The old Makefile also
didn't support that. But loosing the ability to regenerate the C source
is not an option either.
Harald Welte
Alexander Huemer
Daniel Willmann