Impossible: CodeGenUtilX64.compile_c_call_auto: at most 6 arguments are supported

This limit is [imposed here](https://github.com/melsman/mlkit/blob/1733d3d90fc3ebd6157e1c34bcd68de51ab0d722/src/Compiler/Backend/X64/CodeGenUtilX64.sml#L724-L733). Would it be possible to raise it? Is there a workaround?