Update latest.Dockerfile

latest.Dockerfile

@@ -52,6 +52,9 @@ RUN cd /tmp \
   ## Configure and build
   && ./boot.source \
   && ./configure \
+    --build=$(uname -m)-alpine-linux \
+    --host=$(uname -m)-alpine-linux \
+    --target=$(uname -m)-alpine-linux \
   ## Use the LLVM backend
   ## Switch llvm-targets from unknown-linux-gnueabihf->alpine-linux
   ## so we can match the llvm vendor string alpine uses