Meet Error: need the dylink section to be first & how to build libavcodec as wasm side module

**I tried:**
build-with-docker.sh

echo "FFMPEG_EM_FLAGS=${FLAGS[@]}"
emmake make -j
\# emcc "${FLAGS[@]}"

emcc "${FLAGS[@]}" **-s SIDE_MODULE=2**

**And got:**

AR libavcodec/libavcodec.a
LD libavcodec/libavcodec.so.58
emcc: warning: linking a library with `-shared` will emit a static object file. This is a form of emulation to support existing build systems. If you want to build a runtime shared library use the SIDE_MODULE setting. [-Wemcc]
emcc: warning: ignoring unsupported linker flag: `-soname` [-Wlinkflags]
emcc: warning: ignoring unsupported linker flag: `--version-script` [-Wlinkflags

**And in the browser:**

@jeromewu any ideas? thanks a lot.