First work for Windows multi-arch support

Makefile

@@ -21,6 +21,10 @@ ANDROID_TARGETS := $(foreach t, $(BUILD_TYPES),     \
 
 IOS_TARGETS := ios/release
 
+# These can be overriden on the command line, e.g. "make electron TARGET_ARCH=x86 CARGO_ARCH=i686-pc-windows-msvc"
+TARGET_ARCH := x64
+CARGO_ARCH := x86_64-pc-windows-msvc
+
 help:
 	$(Q) echo "The following build targets are supported:"
 	$(Q) echo "  ios      -- download WebRTC and build for the iOS platform"
@@ -72,10 +76,10 @@ electron:
 	fi
 	$(Q) if [ "$(TYPE)" = "debug" ] ; then \
 		echo "Electron: Debug build" ; \
-		./bin/build-electron -d ; \
+		TARGET_ARCH=$(TARGET_ARCH) CARGO_ARCH=$(CARGO_ARCH) ./bin/build-electron -d ; \
 	else \
 		echo "Electron: Release build" ; \
-		./bin/build-electron -r ; \
+		TARGET_ARCH=$(TARGET_ARCH) CARGO_ARCH=$(CARGO_ARCH) ./bin/build-electron -r ; \
 	fi
 	$(Q) (cd src/node && yarn install && yarn build)
 

bin/build-electron

@@ -10,6 +10,9 @@ set -e
 BIN_DIR="$(realpath -e $(dirname $0))"
 . "${BIN_DIR}/env.sh"
 
+TARGET_ARCH=${TARGET_ARCH:-x64}
+CARGO_ARCH=${CARGO_ARCH:-x86_64-pc-windows-msvc}
+
 usage()
 {
     echo 'usage: build-electron [-d|-r|-c]
@@ -90,10 +93,10 @@ export MACOSX_DEPLOYMENT_TARGET="10.10"
 
     if [ "${BUILD_TYPE}" = "debug" ]
     then
-        gn gen -C out/Debug "--args=use_custom_libcxx=false rtc_build_examples=false rtc_build_tools=false rtc_include_tests=false rtc_enable_protobuf=false rtc_use_x11=false rtc_enable_sctp=false"
+        gn gen -C out/Debug "--args=use_custom_libcxx=false target_cpu=\"${TARGET_ARCH}\" rtc_build_examples=false rtc_build_tools=false rtc_include_tests=false rtc_enable_protobuf=false rtc_use_x11=false rtc_enable_sctp=false"
         ninja -C out/Debug
     else
-        gn gen -C out/Release "--args=use_custom_libcxx=false rtc_build_examples=false rtc_build_tools=false rtc_include_tests=false rtc_enable_protobuf=false rtc_use_x11=false is_debug=false rtc_enable_sctp=false"
+        gn gen -C out/Release "--args=use_custom_libcxx=false target_cpu=\"${TARGET_ARCH}\" rtc_build_examples=false rtc_build_tools=false rtc_include_tests=false rtc_enable_protobuf=false rtc_use_x11=false is_debug=false rtc_enable_sctp=false"
         ninja -C out/Release
     fi
 )
@@ -104,9 +107,9 @@ export MACOSX_DEPLOYMENT_TARGET="10.10"
 
     if [ "${BUILD_TYPE}" = "debug" ]
     then
-        npm_config_arch=x64 npm_config_target_arch=x64 npm_config_disturl=https://atom.io/download/electron npm_config_runtime=electron npm_config_target=11.2.0 npm_config_build_from_source=true npm_config_devdir=~/.electron-gyp cargo build --features electron
+        npm_config_arch=${TARGET_ARCH} npm_config_target_arch=${TARGET_ARCH} npm_config_disturl=https://atom.io/download/electron npm_config_runtime=electron npm_config_target=11.2.0 npm_config_build_from_source=true npm_config_devdir=~/.electron-gyp cargo build --target ${CARGO_ARCH} --features electron
     else
-        npm_config_arch=x64 npm_config_target_arch=x64 npm_config_disturl=https://atom.io/download/electron npm_config_runtime=electron npm_config_target=11.2.0 npm_config_build_from_source=true npm_config_devdir=~/.electron-gyp RUSTFLAGS="-C link-arg=-s" cargo build --features electron --release
+        npm_config_arch=${TARGET_ARCH} npm_config_target_arch=${TARGET_ARCH} npm_config_disturl=https://atom.io/download/electron npm_config_runtime=electron npm_config_target=11.2.0 npm_config_build_from_source=true npm_config_devdir=~/.electron-gyp RUSTFLAGS="-C link-arg=-s" cargo build --target ${CARGO_ARCH} --features electron --release
     fi
 
     if [ $DEFAULT_PLATFORM = "darwin" ]
@@ -116,7 +119,7 @@ export MACOSX_DEPLOYMENT_TARGET="10.10"
     elif [ $DEFAULT_PLATFORM = "win32" ]
     then
         mkdir -p ../node/build/win32
-        cp -f target/${BUILD_TYPE}/ringrtc.dll ../node/build/win32/libringrtc.node
+        cp -f target/${CARGO_ARCH}/${BUILD_TYPE}/ringrtc.dll ../node/build/win32/libringrtc-${TARGET_ARCH}.node
     elif [ $DEFAULT_PLATFORM = "linux" ]
     then
         mkdir -p ../node/build/linux