Code review comment for ~epics-core/epics-base/+git/asLib:as-hostname

Successfully tested this patch w/ pvAccess gwdev branch and pva2pva d7314ea from mdavidsaver.

Tested IOC and ca-gateway instances w/ asCheckClientIP=0 and asCheckClientIP=1.
ca-gateway was based on R2-1-1-0 with inline code to set asCheckClientIP.

No changes were needed to pcas version 4.13.2.

With asCheckClientIP=0, a hacked caput can bypass ASG RULES using hostnames.
With asCheckClientIP=1, caput can only spoof username

For pvput and IOC testing:
With asCheckClientIP=0, All ASG RULES using HAG deny write access.
With asCheckClientIP=1, pvput works same as CA for all UAG and HAG based ASG RULES. (Didn't test variables in RULES or spoofing username in pvput.)

Also tested w/ new p4p gateway as a client while p4p gateway is running it's own access security.