debian: Package the installed Python files, not those from the source tree.

debian: Package the installed Python files, not those from the source tree.

The only difference between the Python files that are installed and the
Python files found in the source tree is in the ovs.dirs module, but this
is a very important difference: we want the directories used to be the ones
configured in (e.g. /usr/share/openvswitch), not the only used by default
by the source tree's dirs.py (e.g. /usr/local/share/openvswitch).

I verified with "dpkg-deb -x" and "diff -ur" that in fact this is the only
change that this commit makes.

This bug has been in place since at least commit 1d273d6d8 "debian: Rename
openvswitch-python to python-openvswitch" from over a year ago, but until
now the packaged Python files didn't actually use any directories that
differed between the two versions of dirs.py, so only now has the problem
manifested.

This problem prevented ovs-monitor-ipsec from finding the OVSDB schema
file.

Reported-by: Ethan Jackson <ethan@nicira.com>