building from source on raspbian
I'm trying to build from source according to instructions for Ubuntu 20.04:
```
sudo apt update && sudo apt install git build-essential cmake pkg-config libssl-dev libzmq3-dev libunbound-dev libsodium-dev libunwind8-dev liblzma-dev libreadline6-dev libldns-dev libexpat1-dev libpgm-dev qttools5-dev-tools libhidapi-dev libusb-1.0-0-dev libprotobuf-dev protobuf-compiler libudev-dev libboost-chrono-dev libboost-date-time-dev libboost-filesystem-dev libboost-locale-dev libboost-program-options-dev libboost-regex-dev libboost-serialization-dev libboost-system-dev libboost-thread-dev ccache doxygen graphviz
git clone --recursive https://github.com/monero-project/monero/
cd monero
git checkout release-v0.17
git submodule sync && git submodule update --init --force --recursive
make release-static -j$(nproc)
```

but fails with this:
```
[ 13%] Building C object external/miniupnp/miniupnpc/CMakeFiles/testminiwget.dir/upnpreplyparse.c.o
[ 14%] Building C object external/miniupnp/miniupnpc/CMakeFiles/testminiwget.dir/minixml.c.o
[ 14%] Building C object external/miniupnp/miniupnpc/CMakeFiles/testigddescparse.dir/minisoap.c.o
CMake Error: failed to create symbolic link 'libminiupnpc.so.17': function not implemented
CMake Error: cmake_symlink_library: System Error: Function not implemented
CMake Error: failed to create symbolic link 'libminiupnpc.so': function not implemented
CMake Error: cmake_symlink_library: System Error: Function not implemented
make[3]: *** [external/miniupnp/miniupnpc/CMakeFiles/libminiupnpc-shared.dir/build.make:295: external/miniupnp/miniupnpc/libminiupnpc.so.2.2.1] Error 1
make[3]: *** Deleting file 'external/miniupnp/miniupnpc/libminiupnpc.so.2.2.1'
make[3]: Leaving directory '/mnt/monero/build/Linux/release-v0.17/release'
make[2]: *** [CMakeFiles/Makefile2:1107: external/miniupnp/miniupnpc/CMakeFiles/libminiupnpc-shared.dir/all] Error 2
make[2]: *** Waiting for unfinished jobs....
[ 14%] Building C object external/miniupnp/miniupnpc/CMakeFiles/testigddescparse.dir/connecthostport.c.o
[ 14%] Building C object external/miniupnp/miniupnpc/CMakeFiles/testminiwget.dir/igd_desc_parse.c.o
[ 14%] Building C object external/miniupnp/miniupnpc/CMakeFiles/libminiupnpc-static.dir/listdevices.c.o
[ 14%] Building C object external/miniupnp/miniupnpc/CMakeFiles/libminiupnpc-static.dir/addr_is_reserved.c.o
[ 15%] Building C object external/miniupnp/miniupnpc/CMakeFiles/testminiwget.dir/connecthostport.c.o
[ 15%] Linking C static library libminiupnpc.a
[ 15%] Building C object external/miniupnp/miniupnpc/CMakeFiles/testminiwget.dir/portlistingparse.c.o
make[3]: Leaving directory '/mnt/monero/build/Linux/release-v0.17/release'
[ 15%] Building C object external/miniupnp/miniupnpc/CMakeFiles/testigddescparse.dir/portlistingparse.c.o
[ 15%] Built target libminiupnpc-static
[ 15%] Building C object external/miniupnp/miniupnpc/CMakeFiles/testminiwget.dir/receivedata.c.o
[ 15%] Building C object external/miniupnp/miniupnpc/CMakeFiles/testminiwget.dir/addr_is_reserved.c.o
[ 15%] Building C object external/miniupnp/miniupnpc/CMakeFiles/testigddescparse.dir/receivedata.c.o
[ 15%] Building C object external/miniupnp/miniupnpc/CMakeFiles/testigddescparse.dir/addr_is_reserved.c.o
[ 16%] Linking C executable testminiwget
[ 18%] Linking C executable testigddescparse
make[3]: Leaving directory '/mnt/monero/build/Linux/release-v0.17/release'
[ 18%] Built target testminiwget
make[3]: Leaving directory '/mnt/monero/build/Linux/release-v0.17/release'
[ 18%] Built target testigddescparse
make[2]: Leaving directory '/mnt/monero/build/Linux/release-v0.17/release'
make[1]: *** [Makefile:141: all] Error 2
make[1]: Leaving directory '/mnt/monero/build/Linux/release-v0.17/release'
make: *** [Makefile:107: release-static] Error 2
```
Any ideas how to solve this?
Thanks