Reorganize dockerfile template slightly (same result)

docker/Dockerfile.j2

@@ -143,33 +143,26 @@ ENV CC_aarch64_unknown_linux_gnu="/usr/bin/aarch64-linux-gnu-gcc"
 ENV CROSS_COMPILE="1"
 ENV OPENSSL_INCLUDE_DIR="/usr/include/aarch64-linux-gnu"
 ENV OPENSSL_LIB_DIR="/usr/lib/aarch64-linux-gnu"
+RUN rustup target add aarch64-unknown-linux-gnu
 {%   elif "arm32v6" in target_file %}
 ENV CC_arm_unknown_linux_gnueabi="/usr/bin/arm-linux-gnueabi-gcc"
 ENV CROSS_COMPILE="1"
 ENV OPENSSL_INCLUDE_DIR="/usr/include/arm-linux-gnueabi"
 ENV OPENSSL_LIB_DIR="/usr/lib/arm-linux-gnueabi"
+RUN rustup target add arm-unknown-linux-gnueabi
 {%   elif "arm32v7" in target_file %}
 ENV CC_armv7_unknown_linux_gnueabihf="/usr/bin/arm-linux-gnueabihf-gcc"
 ENV CROSS_COMPILE="1"
 ENV OPENSSL_INCLUDE_DIR="/usr/include/arm-linux-gnueabihf"
 ENV OPENSSL_LIB_DIR="/usr/lib/arm-linux-gnueabihf"
+RUN rustup target add armv7-unknown-linux-gnueabihf
 {%   endif -%}
-{% endif -%}
-
-{% if "alpine" in target_file %}
+{% else -%}
 {%   if "amd64" in target_file %}
 RUN rustup target add x86_64-unknown-linux-musl
 {%   elif "arm32v7" in target_file %}
 RUN rustup target add armv7-unknown-linux-musleabihf
 {%   endif %}
-{% elif "alpine" not in target_file %}
-{%   if "arm64v8" in target_file %}
-RUN rustup target add aarch64-unknown-linux-gnu
-{%   elif "arm32v6" in target_file %}
-RUN rustup target add arm-unknown-linux-gnueabi
-{%   elif "arm32v7" in target_file %}
-RUN rustup target add armv7-unknown-linux-gnueabihf
-{%   endif %}
 {% endif %}
 
 # Builds your dependencies and removes the