CI: Make bashate happy

Bashate warned on init-swift.sh because of E043 -- arithmetic
compound has inconsistent return semantics: (( next_port++ ))
New Zuul reported that on every change as a warning.
This is fixed here.

This change makes Bashate always produce errors so that we do not
introduce such warnings again.

Change-Id: I40166b377ec2580e17901375b636183bca492d3a

tests/init-swift.sh

@@ -44,7 +44,7 @@ function init_swift_logged {
             /etc/kolla/config/swift/$ring.builder
 
         # next ring = next port
-        (( next_port++ ))
+        next_port=$((next_port+1))
     done
 }
 

tools/run-bashate.sh

@@ -1,7 +1,10 @@
 #!/bin/bash
 
 # Ignore E006 -- line length greater than 80 char
+# Error on E005 -- file does not begin with #! or have .sh prefix
+# Error on E042 -- local declaration hides errors
+# Error on E043 -- arithmetic compound has inconsistent return semantics
 
 ROOT=$(readlink -fn $(dirname $0)/.. )
 find $ROOT -not -wholename \*.tox/\* -and -not -wholename \*.test/\* \
-    -and -name \*.sh -print0 | xargs -0 bashate -v --ignore E006
+    -and -name \*.sh -print0 | xargs -0 bashate -v --ignore E006 --error E005,E042,E043