WIP: Opencl to SPIR-V ahead-of-time compilation

This does not yet use the pystencils' cache folder or disk caching of the compilation.

This can be used to embed compiled bytecode into waLBerla executables as I do with my Vulkan wrapper. Not sure if this is a good way to go but at least we can experiment with it.

A good way to proceed with this MR is also a comparison between hip/sicl/ocl/vulkan in order to identify a suitable backend for pystencils.

pystencils/backends/cbackend.py

@@ -23,7 +23,7 @@ except ImportError:
     try:
         from sympy.printing.ccode import CCodePrinter  # for sympy versions < 1.1
     except ImportError:
-        from sympy.printing.cxx import CXX11CodePrinter as CCodePrinter  # for sympy versions > 1.6
+        from sympy.printing.c import C11CodePrinter as CCodePrinter  # for sympy versions > 1.6
 
 __all__ = ['generate_c', 'CustomCodeNode', 'PrintNode', 'get_headers', 'CustomSympyPrinter']