[AWS] check mode for ec2_elb and elb_instance (#42694)

what ELBs an instance will be deregistered from prior to actually
executing

lib/ansible/modules/cloud/amazon/ec2_elb.py

@@ -332,6 +332,7 @@ def main():
 
     module = AnsibleModule(
         argument_spec=argument_spec,
+        supports_check_mode=True
     )
 
     if not HAS_BOTO:
@@ -359,6 +360,7 @@ def main():
                 msg = "ELB %s does not exist" % elb
                 module.fail_json(msg=msg)
 
+    if not module.check_mode:
         if module.params['state'] == 'present':
             elb_man.register(wait, enable_availability_zone, timeout)
         elif module.params['state'] == 'absent':

lib/ansible/modules/cloud/amazon/elb_instance.py

@@ -328,6 +328,7 @@ def main():
 
     module = AnsibleModule(
         argument_spec=argument_spec,
+        supports_check_mode=True
     )
 
     if not HAS_BOTO:
@@ -355,6 +356,7 @@ def main():
                 msg = "ELB %s does not exist" % elb
                 module.fail_json(msg=msg)
 
+    if not module.check_mode:
         if module.params['state'] == 'present':
             elb_man.register(wait, enable_availability_zone, timeout)
         elif module.params['state'] == 'absent':