Fix DESTDIR and prefix when installing Python files.
Fix DESTDIR and prefix when installing Python files.

I added DESTDIR to src/python/Makefile.in some time ago, but I did
it wrong, because I didn't understand distutils well.
In order to install to DESTDIR with distutils, one says
python setup.py --root="${DESTDIR}" --prefix="${prefix}",
rather than
python setup.py --prefix="${DESTDIR}${prefix}"

This patch also removes remaining uses of DESTDIR while constructing
paths.py.  Installed files should never contain a reference to $DESTDIR,
since it is only a staging area.

razr/speechd,razr/speechd,razr/speechd,razr/speechd