Look into using clang to generate bindings instead of xndtools

[saulshanabrook]

Currently, we parse some of the xnd/ndtypes/gumath c files to generate compatible LLVM functions that can call their exposed functions. We do this by parsing the C files in Python.

Instead, we could use clang itself to generate these bindings. That way we don't have to reimplement a C parser and define the mappings between C and LLVM ABIs ourselves.

See aguinet/dragonffi#13 for some discussion using dragonffi to do this (it has a Python API)