build: switch to ordinary auto* tools system.

build: switch to ordinary auto* tools system.

Benefits:

1. If a header file gets modified, all dependent stuff gets rebuilt.
   No need for 'make clean' after each header modification, no more
   spurious errors, no more spurious rebuilds.
2. No more errors due to redefined preprocessor, compiler, and linker
   FLAGS.
3. Build scripts don't try to build every *.cc file which happen to
   lurk in the source directory.