v6.15.2 at the time of this writing

• download xmrig: https://github.com/xmrig/xmrig/releases
• copy xmrig/scripts to xmrig-proxy/scripts
• $ cp -frv xmrig/scripts xmrig-proxy/
• $ cd xmrig-proxy && scripts/build_deps.sh
• edit cmake/cmake.flags
• find set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -static-libgcc -static-libstdc++") and add -static to it
• result: set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -static-libgcc -static-libstdc++ -static")
• $ mkdir -p build && cd build