Update links in Dockerfile.raspberrypi

Some links used in Dockerfile.raspberrypi are not accessible anymore,
because they were pointing to old versions of some source packages and
new versions were released.  This commit fixes this by changing the
links to point to the newest versions.

Dockerfile.raspberrypi

@@ -17,7 +17,7 @@ ENV TOOL_BIN_DIR /tools/arm-bcm2708/gcc-linaro-$HOST-raspbian-x64/bin
 ENV PATH ${TOOL_BIN_DIR}:$PATH
 
 RUN mkdir $LOCAL_DIR && mkdir zlib && cd zlib && \
-   curl -Ls -o - 'http://zlib.net/zlib-1.2.8.tar.gz'  | \
+   curl -Ls -o - 'http://zlib.net/zlib-1.2.11.tar.gz'  | \
         tar xzf - --strip-components=1 && \
    prefix=${LOCAL_DIR} \
    CC=$HOST-gcc \
@@ -31,7 +31,7 @@ RUN mkdir $LOCAL_DIR && mkdir zlib && cd zlib && \
    make -s install
 
 RUN mkdir -p expat && cd expat && \
-    curl -Ls -o - 'http://sourceforge.net/projects/expat/files/latest/download' | \
+    curl -Ls -o - 'https://sourceforge.net/projects/expat/files/expat/2.2.0/expat-2.2.0.tar.bz2/download' | \
         tar xjf - --strip-components=1 && \
     ./configure \
         --host=$HOST \