Incorrect C header generated on typed enum

[kennykwok]

On Rust,

#[repr(i32)
pub enum MyEnum {
   EnumA,
   EnumB,
}

The generated C header is wrong (with duplicated definitions):

enum MyEnum {
   EnumA,
   EnumB
};
typedef int32_t MyEnum;

To fix the duplicated definitions, the C header should be like this:

enum {
   EnumA,
   EnumB
};
typedef int32_t MyEnum;

In additional, with cpp_compat = true, the C/C++ compatible header should be like this:

enum
#ifdef __cplusplus
 MyEnum : int32_t
#endif // __cplusplus
{
   EnumA,
   EnumB
};
#ifndef __cplusplus
typedef int32_t MyEnum;
#endif // __cplusplus

[kennykwok]

I think it can be fixed in write_tag_enum() by pushing the write (that need specify size) of the tag_name inside if config.cpp_compatible_c() { ... }