gdc --version doesn't indicate which D front-end version it's compatible with

[singingbush]

not sure where is best placed for this but on my Fedora system 
running `gdc --version` gives me pretty much the same output as 
`gcc --version`

GDC:

```
$ gdc --version
gdc (GCC) 11.2.1 20211203 (Red Hat 11.2.1-7)
Copyright (C) 2021 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  
There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A 
PARTICULAR PURPOSE.
```

GCC:

```
$ gcc --version
gcc (GCC) 11.2.1 20211203 (Red Hat 11.2.1-7)
Copyright (C) 2021 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  
There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A 
PARTICULAR PURPOSE.
```

It would be far more helpful if running `gdc --version` gave some 
indication of the version of D it's aligned to (which was 2.076 
last time I checked).