ubuntu-win64-cross: Add zstd to build tools

Author: mborgerson

ubuntu-win64-cross/gcc.Dockerfile

@@ -54,7 +54,8 @@ RUN apt-get update \
         software-properties-common \
         unzip \
         wget \
-        xz-utils
+        xz-utils \
+        zstd
 
 RUN git clone ${MXE_REPO} ${MXE_PATH} \
  && cd ${MXE_PATH} \

ubuntu-win64-cross/llvm.Dockerfile

@@ -32,7 +32,8 @@ RUN apt-get update \
         python3-venv \
         python3-yaml \
         ruby \
-        zip
+        zip \
+        zstd
 
 WORKDIR /usr/local
 RUN git clone -b ${MXE_TAG} --single-branch ${MXE_REPO}