Update scripts/build.sh to build coap-etsi_iot_01 and coap-tiny examples

Travis now checks exmples continue to build, even if there is an API
change.

scripts/build.sh

@@ -38,7 +38,7 @@ case "${PLATFORM}" in
                make -C examples/lwip
              ;;
     posix|*) config "$WITH_TESTS $WITH_DOCS --enable-examples $WITH_TLS" && \
-               make
+               make && make check
              ;;
 esac