package version and variant info in `main.log`

[Ryan Schmidt]

> On Nov 8, 2019, at 02:39, Werner LEMBERG wrote:
> 
>>> I've noticed that in `main.log` files there is no information what
>>> version and variants have been requested – for example,
>>> 
>>> ImageMagick @6.9.9-40_7+x11
>>> 
>>> Wouldn't it make sense to make `port` add this information to the
>>> very top of `main.log`? This would also help identify various
>>> `make.log` files more easily.
>> 
>> If that's not already in there,
> 
> It seems so.
> 
>> then yes, that would be good to have.
> 
> OK.  Shall I open a ticket?

Sure