Crosscompile instructions:
* Build docker image with python armv7 installed:
    `docker build -t my-image .`
* Use cross to crosscompile:
    `cross.exe build --target=armv7-unknown-linux-gnueabihf --release`
* Move built library to the correct folder:
    `cp fastproot/target/armv7-unknown-linux-gnueabihf/release/libfastproot.so ./`
* Move windows binary
    `cp fastproot/target/release/fastproot.dll ./fastproot.pyd`