Revert r66415. It's causing failures during bootstrap builds:

Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://developer.apple.com/bugreporter> for instructions.
/Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvmgcc42.roots/llvmgcc42~obj/src/gcc/libgcc2.c: In function '__muldi3':
/Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvmgcc42.roots/llvmgcc42~obj/src/gcc/libgcc2.c:567: internal compiler error: Bus error
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://developer.apple.com/bugreporter> for instructions.
/Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvmgcc42.roots/llvmgcc42~obj/src/gcc/libgcc2.c: In function '__lshrdi3':
/Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvmgcc42.roots/llvmgcc42~obj/src/gcc/libgcc2.c:421: internal compiler error: Bus error
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://developer.apple.com/bugreporter> for instructions.
make[5]: *** [libgcc/./_lshrdi3.o] Error 1
make[5]: *** Waiting for unfinished jobs....
make[5]: *** [libgcc/./_muldi3.o] Error 1
make[5]: *** [libgcc/./_negdi2.o] Error 1


--- Reverse-merging (from foreign repository) r66415 into '.':
U    include/llvm/BasicBlock.h
U    include/llvm/ADT/ilist_node.h
U    include/llvm/CodeGen/SelectionDAG.h
U    include/llvm/CodeGen/MachineFunction.h
U    include/llvm/CodeGen/MachineBasicBlock.h
U    include/llvm/Function.h

llvm-svn: 66426