They build fine for me, compiling 3109 x64 as we speak.
Try to Clean the solution, remove the artifact folders by hand, and see if it works after that.
Unspecified error sounds familiar tho, did you break your x64 compiler by chance?
__________________
Dolphin Rev 4597 Download: Dolphin 32-bit | Dolphin 64-bit | Older Revs
Both Jit and JitIL in one Archive. Copy over your own "User"-Folder to keep your settings.
Taking requests for special revisions/compiles aswell.