Draft: C Interfacing

This MR enables C compatibility for the generated target code

• Adds SfgConfig.c_interfacing option that automatically marks all function declarations as extern "C"
• Provides hybrid compilation mode for header files where C/C++ includes and also function definitions are guarded by

#ifdef __cplusplus 
<cpp includes...>

#define EXTERNC extern "C"
#else 
<hybrid includes...>

#define EXTERN C
#endif

• Automatically converts C++ header includes, e.g. <cstdint>, to C compatible header includes, e.g. <stdint.h>, for hybrid mode

src/pystencilssfg/emission/file_printer.py

@@ -103,7 +103,7 @@ class SfgFilePrinter:
             case SfgKernelHandle(kernel):
                 kernel_printer = CAstPrinter(
                     indent_width=self._indent_width,
-                    func_prefix="inline" if declared_entity.inline else "",
+                    func_prefix="inline" if declared_entity.inline else None,
                 )
                 return kernel_printer.print_signature(kernel) + ";"