configure: check for uuid python module

configure: check for uuid python module

After introducing commit a5ae88ff8a276e86c842ac102145432662bf711a
"ovsdb-doc: generate vswitch.[pic|gv] files only if dot tool is
available" Open vSwitch did not build anymore on hosts that did not
have uuid python module installed (for example, we still support
XenServer that still uses old python 2.4 and hence does not have uuid).

After this commit ./configure will check whether uuid module is present
and, if it isn't, then it will add python/compat to the PYTHONPATH.

Acked-By: Ben Pfaff <blp@nicira.com>
Signed-Off-By: Ansis Atteka <aatteka@nicira.com>
Issue: 20476