Add Qt5 for wasm to emscripten image

emscripten/Dockerfile

 FROM ubuntu:18.04
 
+SHELL ["/bin/bash", "-c"]
 RUN apt-get update && \
     apt-get dist-upgrade -y && \
-    apt-get install -y git make python3 cmake nodejs default-jre build-essential && \
+    apt-get install -y git make wget python3 cmake nodejs default-jre build-essential && \
     rm -rf /var/lib/apt/lists/* && \
     git clone https://github.com/juj/emsdk.git && \
     cd emsdk && \
     ./emsdk install 1.40.1 && \
     ./emsdk activate 1.40.1 && \
+    cd / && \
+    source /emsdk/emsdk_env.sh && \
+    wget -q -c https://download.qt.io/archive/qt/5.15/5.15.2/single/qt-everywhere-src-5.15.2.tar.xz && \
+    tar -xf qt-everywhere-src-5.15.2.tar.xz && \
+    rm qt-everywhere-src-5.15.2.tar.xz && \
+    cd qt-everywhere-src-5.15.2 && \
+    ./configure -xplatform wasm-emscripten -nomake examples -nomake tests -opensource -prefix $PWD/qtbase --confirm-license && \
+    make module-qtbase && \
     cd ..