Dockerfile definition and helper scripts related to preparing a toolchain image able to produce WASM binaries

Includes emscripten toolchain like also precompiled libraries:

• boost
• openssl
• sec256k1-zkp

scripts/emscripten/prepare_boost.sh

@@ -14,17 +14,37 @@ git checkout .
 # to fix ambigous generators specific to SEARCH_LIB
 git apply /home/emscripten/scripts/emscripten_toolset.patch
 
-rm -vrf "${INSTALL_PREFIX}/prebuilt_boost"
 rm -vrf "${TMP_SRC}/boost_build/"
 
-mkdir -vp "${INSTALL_PREFIX}/prebuilt_boost"
 mkdir -vp "${TMP_SRC}/boost_build/"
 
 echo "Entering directory: ${TMP_SRC}/boost"
 
 cd "${TMP_SRC}/boost"
 
-./bootstrap.sh --without-icu --with-libraries=system,date_time,filesystem,program_options,headers,chrono --prefix="${INSTALL_PREFIX}/prebuilt_boost"
-./b2 --reconfigure toolset=emscripten link=static runtime-link=static --build-dir="${TMP_SRC}/boost_build/" --prefix="${INSTALL_PREFIX}/prebuilt_boost" \
-    host-os=linux target-os=linux cflags="-s USE_PTHREADS=1 -s USE_ZLIB=1" cxxflags="-s USE_PTHREADS=1 -s USE_ZLIB=1" \
-    install
+./bootstrap.sh --without-icu --prefix="${INSTALL_PREFIX}"
+
+printf "using clang : emscripten : emcc -s USE_ZLIB=1 -s USE_ICU=0 : <archiver>emar <ranlib>emranlib <linker>emlink <cxxflags>\"-std=c++11 -s USE_ICU=0\" ;" | tee -a ./project-config.jam >/dev/null
+
+./b2 \
+  --build-dir="${TMP_SRC}/boost_build/" \
+  --prefix="${INSTALL_PREFIX}" \
+  -j $(nproc) \
+  -q \
+  runtime-link=static \
+  link=static \
+  toolset=clang-emscripten \
+  variant=release \
+  threading=single \
+  --with-atomic \
+  --with-chrono \
+  --with-date_time \
+  --with-filesystem \
+  --with-program_options \
+  --with-regex \
+  --with-system \
+  install
+
+#./b2 --reconfigure threading=single toolset=emscripten link=static runtime-link=static --build-dir="${TMP_SRC}/boost_build/" --prefix="${INSTALL_PREFIX}" \
+#    host-os=linux target-os=linux cflags="-s USE_PTHREADS=0 -s USE_ZLIB=1" cxxflags="-s USE_PTHREADS=0 -s USE_ZLIB=1" \
+#    install