Attempt to display compiler version in configure summary
Attempt to display compiler version in configure summary

For debugging build issues (esp. warnings), it's useful to
know the compiler version, not just the name.

Tricky/moving target in the general case, but this should
work for many.

Nothing breaks if detection fails...

icing/mod_md,icing/mod_md,icing/mod_md,icing/mod_md,icing/mod_md