Add flag to parse matching `#define *` into `enum`s instead of constants

Hi! I have a header file I'd rather not touch, and I want to convert some #define directives that are integers into enums, such that --constified-enum-module, --bitfield-enum etc would work as expected

#define FOO_BAR_A_BAZ 0
#define FOO_BAR_BOB 1
#define FOO_BAR_C 2
#define FOO_BAR_D 3

Given above header, generate the equivalent code as for when parsing

enum FOO_BAR {
    A_BAZ=0,
    BOB=1,
    C=2,
    D=3,
};

This should also keep comments intact.

Is this possible to implement?

Start by tracing how bindgen parses C #define directives and applies --constified-enum-module and --bitfield-enum. Compare that behavior with the generated output for the enum example, preserving comments. Done means matching prefixed defines can become enums and the existing flag behavior remains intact.