Created attachment 88452 [details] [review]
Another approach

I can confirm the issue with Mono's signal handling and the hanging of the
applications. After digging around Mesa, I came up with the attached patch.
Used it successfully with Mesa 9.2.{0,1,2} and git. Probably the fine semantics
are still up to the devs, though the static llvm variable is set in a static
context and thus hopefully early enough.

Anyway I guess the default llvm value for that flag should probably be
inverted.