Update figlet's watchdog

Signed-off-by: Alex Ellis <alexellis2@gmail.com>

sample-functions/figlet/Dockerfile

-FROM alpine:3.8
+FROM openfaas/classic-watchdog:0.14.4 as watchdog
 
-RUN apk --no-cache add curl \
-    && curl -sL https://github.com/openfaas/faas/releases/download/0.13.0/fwatchdog > /usr/bin/fwatchdog \
-    && chmod +x /usr/bin/fwatchdog
+FROM alpine:3.9
+
+COPY --from=watchdog /fwatchdog /usr/bin/fwatchdog
+RUN chmod +x /usr/bin/fwatchdog
 
 RUN apk add --no-cache figlet
 

sample-functions/figlet/Dockerfile.armhf

-FROM alpine:3.8
+FROM openfaas/classic-watchdog:0.14.4 as watchdog
 
-RUN apk --no-cache add curl \
-    && curl -sL https://github.com/openfaas/faas/releases/download/0.13.0/fwatchdog-armhf > /usr/bin/fwatchdog \
-    && chmod +x /usr/bin/fwatchdog
+FROM alpine:3.9
+
+COPY --from=watchdog /fwatchdog /usr/bin/fwatchdog
+RUN chmod +x /usr/bin/fwatchdog
 
 RUN apk add --no-cache figlet
 
@@ -11,3 +12,4 @@ ENV fprocess="figlet"
 
 HEALTHCHECK --interval=5s CMD [ -e /tmp/.lock ] || exit 1
 CMD ["fwatchdog"]
+