-g doc-includes doesn't generate <include> for -g macro-bindings #832

A value-like macro binding (source):

#define B3_PI 3.14159265359f

generates

    [NativeTypeName("#define B3_PI 3.14159265359f")]
    public const float B3_PI = 3.14159265359f;

without the <include> supposedly generated by -g doc-includes