Add armV7 support

docker/Dockerfile

@@ -2,11 +2,12 @@ FROM rust:1.34
 LABEL Description="Rust compile env for Linux + Windows (cross)"
 
 RUN apt update
-RUN apt install -y build-essential mingw-w64 gcc-aarch64-linux-gnu
+RUN apt install -y build-essential mingw-w64 gcc-aarch64-linux-gnu gcc-arm-linux-gnueabihf
 
 RUN rustup target add x86_64-pc-windows-gnu
 RUN rustup target add x86_64-unknown-linux-musl
 RUN rustup target add aarch64-unknown-linux-gnu
+RUN rustup target add armv7-unknown-linux-gnueabihf
 
 # Append the linker to the cargo config for Windows cross compile
 RUN echo "[target.x86_64-pc-windows-gnu]" >> /usr/local/cargo/config && \
@@ -15,5 +16,9 @@ RUN echo "[target.x86_64-pc-windows-gnu]" >> /usr/local/cargo/config && \
 RUN echo "[target.aarch64-unknown-linux-gnu]" >> /usr/local/cargo/config && \
     echo "linker = '/usr/bin/aarch64-linux-gnu-gcc'" >> /usr/local/cargo/config
 
+RUN echo "[target.armv7-unknown-linux-gnueabihf]" >> /usr/local/cargo/config && \
+    echo "linker = '/usr/bin/arm-linux-gnueabihf-gcc-5'" >> /usr/local/cargo/config
+
 ENV CC_x86_64_unknown_linux_musl="gcc" 
 ENV CC_aarch64_unknown_linux_gnu="aarch64-linux-gnu-gcc" 
+ENV CC_armv7_unknown_linux_gnueabhihf="arm-linux-gnueabihf-gcc-5"