Use upstream wasi-sdk

Makefile

@@ -1,5 +1,6 @@
 BUILD := build
 ICU_DATA_FILTER_FILE := $(CURDIR)/data-filters/swift-minimal.json
+WASI_LIBC_EMULATION_FLAGS := -D_WASI_EMULATED_SIGNAL
 
 $(BUILD)/icu4c-src.tgz:
 	mkdir -p $(@D)
@@ -45,8 +46,8 @@ endif
 	    --with-data-packaging=static \
 	    CC="$(WASI_SDK_PATH)/bin/clang" CXX="$(WASI_SDK_PATH)/bin/clang++" \
 	    AR="$(WASI_SDK_PATH)/bin/llvm-ar" RANLIB="$(WASI_SDK_PATH)/bin/llvm-ranlib" \
-	    CFLAGS="--sysroot $(WASI_SDK_PATH)/share/wasi-sysroot" \
-	    CXXFLAGS="-fno-exceptions --sysroot $(WASI_SDK_PATH)/share/wasi-sysroot" && \
+	    CFLAGS="--sysroot $(WASI_SDK_PATH)/share/wasi-sysroot $(WASI_LIBC_EMULATION_FLAGS)" \
+	    CXXFLAGS="-fno-exceptions --sysroot $(WASI_SDK_PATH)/share/wasi-sysroot $(WASI_LIBC_EMULATION_FLAGS)"
 	  $(MAKE) && \
 	  $(MAKE) install DESTDIR=$(CURDIR)/$(BUILD)/icu4c-out/cross/install/icu
 	touch $@

ci/install-build-sdk.sh

@@ -3,16 +3,7 @@ set -xe
 
 : ${BUILD_DIR:?"BUILD_DIR is missing"}
 
-mkdir -p $BUILD_DIR/ci
+mkdir -p $BUILD_DIR/ci/wasi-sdk
 
-# install the Wasi SDK
-wget -O $BUILD_DIR/ci/dist-wasi-sdk.tgz.zip "https://github.com/swiftwasm/wasi-sdk/releases/download/0.2.0-swiftwasm/dist-ubuntu-latest.tgz.zip"
-unzip $BUILD_DIR/ci/dist-wasi-sdk.tgz.zip -d $BUILD_DIR/ci
-WASI_SDK_TAR_PATH=$(find $BUILD_DIR/ci -type f -name "wasi-sdk-*")
-WASI_SDK_FULL_NAME=$(basename $WASI_SDK_TAR_PATH -linux.tar.gz)
-tar xfz $WASI_SDK_TAR_PATH -C $BUILD_DIR/ci
-mv $BUILD_DIR/ci/$WASI_SDK_FULL_NAME $BUILD_DIR/ci/wasi-sdk
-
-# Link wasm32-wasi-unknown to wasm32-wasi because clang finds crt1.o from sysroot
-# with os and environment name `getMultiarchTriple`.
-ln -s wasm32-wasi $BUILD_DIR/ci/wasi-sdk/share/wasi-sysroot/lib/wasm32-wasi-unknown
+curl -L -o $BUILD_DIR/ci/dist-wasi-sdk.tar.gz "https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-20/wasi-sdk-20.0-linux.tar.gz"
+tar -xzf $BUILD_DIR/ci/dist-wasi-sdk.tar.gz --strip-components=1 -C $BUILD_DIR/ci/wasi-sdk