This dockerfile is designed to allow c++ programs to be statically built using dockcross, 
natively for x86_64 and cross-compiling for arm64 linux architectures (for raspberry pi's and quest 3 headsets), and link statically to these libraries built in the docker container:
- nlohmann/json https://github.com/nlohmann/json
- libassert from https://github.com/jeremy-rifkin/libassert

plus has the header for httplib ( https://github.com/yhirose/cpp-httplib ) in /usr/local/include.