Add libclang-dev, more environment variables

Dockerfile

@@ -3,6 +3,11 @@ ARG TARGET
 # build environment
 FROM rustembedded/cross:$TARGET
 
+RUN \
+  apt update && \
+  apt upgrade -y && \
+  apt install libclang-dev
+
 ARG UID=991
 ARG GID=991
 ARG TARGET
@@ -15,7 +20,11 @@ ENV \
   TARGET=${TARGET} \
   TOOL=${TOOL} \
   BUILD_MODE=${BUILD_MODE} \
-  TOOLCHAIN=stable
+  TOOLCHAIN=stable \
+  CC=${TOOL}-cc \
+  CXX=${TOOL}-c++ \
+  BINDGEN_EXTRA_CLANG_ARGS="--sysroot=/usr/local/$TOOL/ --target=$TARGET -L/usr/local/$TOOL/lib -I/usr/local/$TOOL/include --static -static-libgcc -static-libstdc++" \
+  RUSTFLAGS="-C target-feature=+crt-static -L/usr/local/$TOOL/lib"
 
 RUN \
   addgroup --gid "${GID}" build && \