Fixes docker files

This adds GCC, and changes options to correspond with
changes open62541 has had.
It only builds shared libs and copies/installs them

Dockerfile

@@ -2,7 +2,9 @@ FROM alpine:3.3
 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
+RUN cmake -DUA_ENABLE_AMALGAMATION=true  \
+          -DBUILD_SHARED_LIBS=true \
+          /tmp/open62541 
+RUN make -j
 RUN cp *.h /usr/include/ && \
-    cp *.so /usr/lib && \
-    cp *.a /usr/lib
+    cp *.so /usr/lib

TinyDockerfile

@@ -2,10 +2,10 @@ FROM alpine:3.3
 ADD . /tmp/open62541
 WORKDIR /tmp/open62541/build
 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 && \
+    cmake -DUA_ENABLE_AMALGAMATION=true \
+          -DBUILD_SHARED_LIBS=true /tmp/open62541 && \
     make && \
     cp *.h /usr/include/ && \
     cp *.so /usr/lib && \
-    cp *.a /usr/lib && \
     make clean && \
-    apk del cmake gcc musl-dev python make
+    apk del cmake gcc g++ musl-dev python make