TT#21905 Switch libtcap Dockerfile to Debian stretch

Change-Id: I597d965da717a76517523075c33296f908f0804f

t/Dockerfile

@@ -1,11 +1,11 @@
-# DOCKER_NAME=libtcap-jessie
+# DOCKER_NAME=libtcap-stretch
-FROM docker.mgm.sipwise.com/sipwise-jessie:latest
+FROM docker.mgm.sipwise.com/sipwise-stretch:latest
 
 # Important! Update this no-op ENV variable when this Dockerfile
 # is updated with the current date. It will force refresh of all
 # of the base images and things like `apt-get update` won't be using
 # old cached versions when the Dockerfile is built.
-ENV REFRESHED_AT 2016-05-31
+ENV REFRESHED_AT 2017-09-25
 
 RUN apt-get update
 RUN apt-get install --assume-yes git abi-compliance-checker
@@ -18,12 +18,12 @@ WORKDIR /code/
 # Instructions for usage
 # ----------------------
 # When you want to build the base image from scratch (jump to the next section if you don't want to build yourself!):
-# % docker build --tag="libtcap-jessie" .
+# % docker build --tag="libtcap-stretch" .
-# % docker run --rm -i -t -v $(pwd)/..:/code:rw libtcap-jessie:latest bash
+# % docker run --rm -i -t -v $(pwd)/..:/code:rw libtcap-stretch:latest bash
 #
 # Use the existing docker image:
-# % docker pull docker.mgm.sipwise.com/libtcap-jessie
+# % docker pull docker.mgm.sipwise.com/libtcap-stretch
-# % docker run --rm -i -t -v $(pwd)/..:/code:rw docker.mgm.sipwise.com/libtcap-jessie:latest bash
+# % docker run --rm -i -t -v $(pwd)/..:/code:rw docker.mgm.sipwise.com/libtcap-stretch:latest bash
 #
 # Inside docker (the command is in history, just press UP button):
 #   ./t/testrunner