Fix alpine build

tools/dockerfile/test/cxx_alpine_x64/Dockerfile

@@ -27,7 +27,7 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-FROM alpine:3.3
+FROM alpine:3.5
 
 # Install Git and basic packages.
 RUN apk update && apk add \