.di generator fix

[Satoshi via Digitalmars-d]

https://issues.dlang.org/show_bug.cgi?id=16590
6 months from reporting this bug and there is still no usable 
fix...


How to test:
1. generate di files from druntime and phobos
2. compile any bigger project like vibe.d to .di files instead of 
.d files.
3. fix bugs