Debian: set source format to 3.0 (quilt)

This is my preferred package format as it allows changes
to be added as patches when the Debian package needs to
be updated between upstream releases.

I have been making this change in the Debian packages
so it seems as well to include it upstream.

[Update to debian/automake.mk by Ben Pfaff.]

Author: horms

debian/automake.mk

@@ -42,7 +42,8 @@ EXTRA_DIST += \
 	debian/python-openvswitch.dirs \
 	debian/python-openvswitch.install \
 	debian/rules \
-	debian/rules.modules
+	debian/rules.modules \
+	debian/source/format
 
 check-debian-changelog-version:
 	@DEB_VERSION=`echo '$(VERSION)' | sed 's/pre/~pre/'`;		     \

debian/source/format

@@ -0,0 +1 @@
+3.0 (quilt)