r275115 - Prevent the creation of empty (forwarding) blocks resulting from nested ifs.

[Doug Gilmore via cfe-commits]

This change broke several MIPS builders:

https://dmz-portal.mips.com/bb/builders/LLVM%20with%20integrated%20assembler%20and%20fPIC%20and%20-O0

and 

https://dmz-portal.mips.com/bb/builders/LLVM%20with%20integrated%20assembler%20and%20fPIC%20and%20-O0%20and%20fast%20isel%20and%20mips%20fast%20isel

More information to follow.

Sorry for the delay in tracking this down,

Doug