Fix docker build error - " No CMAKE_CXX_COMPILER could be found."

Dockerfile

@@ -1,5 +1,5 @@
 FROM alpine:3.3
-RUN apk add --no-cache cmake gcc musl-dev python make && rm -rf /var/cache/apk/*
+RUN apk add --no-cache cmake gcc g++ musl-dev python make && rm -rf /var/cache/apk/*
 ADD . /tmp/open62541
 WORKDIR /tmp/open62541/build
 RUN cmake -D UA_ENABLE_AMALGAMATION=true /tmp/open62541 && make

TinyDockerfile

@@ -1,7 +1,7 @@
 FROM alpine:3.3
 ADD . /tmp/open62541
 WORKDIR /tmp/open62541/build
-RUN apk add --no-cache cmake gcc musl-dev python make && rm -rf /var/cache/apk/* && \
+RUN apk add --no-cache cmake gcc g++ musl-dev python make && rm -rf /var/cache/apk/* && \
     cmake -D UA_ENABLE_AMALGAMATION=true /tmp/open62541 && \
     make && \
     cp *.h /usr/include/ && \