Fix cinder-dsvm-apache job
Fix cinder-dsvm-apache job

CINDER_USE_MOD_WSGI=True should be added to devstack config. Exporting
local variable doesn't work on gates.

Change-Id: I47b6155ab8311263e88246730365db6d05325a01

dongwenjuan/project-config,Tesora/tesora-project-config,Tesora/tesora-project-config,openstack-infra/project-config,dongwenjuan/project-config,openstack-infra/project-config,noorul/os-project-config,noorul/os-project-config