[krbdev.mit.edu #7108] Move build system to top level

[Greg Hudson via RT]

Since we are now using configured paths in the documentation build, we 
need it to be reachable from the autoconf-based build system.  The 
solution we have right now is kind of confusing (a directory src/doc 
whose Makefile.in pulls sources from $(top_srcdir)/../doc).

There are a few options here:

* Move everything up from src into the top level (suggested by Tom).  
This would make examining history a bit inconvenient; git log would need 
the --follow option to view history of files across the rename (and that 
doesn't work for directories).  Also, any patches applied downstream 
would need to be reworked.

* Move doc, README, and NOTICE up into src and then start checking 
out/distributing src instead of the top level (suggested by Ken).  
Patches applied downstream would still need to be reworked.

* Just move the build system up a level.  Sam suggested that this is a 
cleaner result anyway.  Patches applied downstream would still be fine 
unless they affect the build system.  However, the changes to the build 
system would be more significant than either of the above options.

All of these options will require changes to how downstream packages 
runs the build, since they will need to run configure from the top level 
instead of from src.  However, it will generally make those packages 
simpler.

More discussion here:

http://mailman.mit.edu/pipermail/krbdev/2012-February/010690.html