deletion proposal: devel/g-wrap

[Greg Troxel <gdt%lexort.com@localhost>]

This is more or less like swig, but written in guile.   The last release
in 2015, nothing uses it in pkgsrc, and I am not aware of any even
semi-maintained program that uses it.   I have inquired about it on the
guile user list.

Asssuming I don't hear from guile people that it's still in use, or
receive objections here, I plan to remove it from pkgsrc no earlier than
October 12.