CTDB: fix version string with vendor trailer comparison

commit 4a31eb7 should handle a -VENDOR trailer
+ e.g. 4.0.0-VendorVersion

however when using the sed from 4a31eb7 on a version string with vendor trailer e.g.

echo "4.0.0-VendorVersion" | awk '{print $NF}' | sed "s/.?:alpha:.*//"

yields

4.0.0-

after fix

echo "4.0.0rc1" | awk '{print $NF}' | sed "s/[-\.]\?:alpha:.*//"
4.0.0

echo "4.0.0-VendorVersion" | awk '{print $NF}' | sed "s/[-\.]\?:alpha:.*//"
4.0.0

echo "4.0.0.GIT.1a2b3c4d" | awk '{print $NF}' | sed "s/[-\.]\?:alpha:.*//"
4.0.0

Fixes: https://github.com/ClusterLabs/resource-agents/issues/1333

Signed-off-by: Noel Power <noel.power@suse.com>