DMD sources: convert glue.c to glue.d

[Walter Bright via Digitalmars-d]

https://github.com/dlang/dmd/pull/6138

This is just another file in the ongoing process to convert DMD from C++ to D. 
It shows that relatively pedestrian C++ code can convert to D with few 
difficulties. There's a 1:1 correspondence between the two, and most edits are 
simply replacing -> and :: with .

Note that no attempt is made to fix anything, change to idiomatic D, improve 
comments, etc. It's a rote translation only.