[D-runtime] [D-Programming-Language/druntime] 871de1: update MANIFEST

[Walter Bright]

Brad Roberts wrote:
> IMHO, this is the wrong direction for makefiles in general.  Duplication of long lists is just asking for them to grow
> out of sync.

I like and use manifests because:

1. Otherwise, it's an error prone pain to figure out what files are 
source and what are generated
2. I use the manifest to copy druntime sources between systems
3. I use the manifest to copy the files to the release directory