[creduce-dev] new pass

[John Regehr]

Yang has added a pass that removes function bodies and C-Reduce is now 
up to 5x faster than 2.1.0 when reducing large C++ codes.  For these 
experiments he compiled against LLVM 185996, which seems to be a good 
version to use for now.  We'd be happy to hear if others' experience 
matches or doesn't match ours.

John