Add alpine3 docker for testing and missing include

Author: dtrugman

docker/Dockerfile-alpine3

@@ -0,0 +1,10 @@
+FROM alpine:3
+
+WORKDIR /pfs
+
+RUN apk add --update cmake alpine-sdk linux-headers
+
+ENV CXX=g++
+ENV CC=gcc
+
+CMD /bin/sh

sample/log.hpp

@@ -18,6 +18,7 @@
 #define SAMPLE_LOG_HPP
 
 #include <iostream>
+#include <cstdint>
 
 #define TAB "\t"
 #define ENDL "\n"