Use Z option for docker-run volume mount

This is necessary on systems with SELinux to prevent file permission/access errors when building WASM output

 * cli/src/wasm.rs: Use Z volume mount option for docker-run
 * script/build-wasm: Likewise.

script/build-wasm

@@ -67,7 +67,7 @@ if which emcc > /dev/null && [[ "$force_docker" == "0" ]]; then
 elif which docker > /dev/null; then
   emcc="docker run               \
     --rm                         \
-    -v $(pwd):/src               \
+    -v $(pwd):/src:Z             \
     -u $(id -u)                  \
     -e EMCC_FORCE_STDLIBS=libc++ \
     trzeci/emscripten-slim       \