Fix DEBUG logs in MachineLICM.
Fix DEBUG logs in MachineLICM.

Summary:
MBBs don't necessarily have a name (in my experience, they almost never
do), in which case this logging is quite unhelpful.  The number seems to
work well.

Reviewers: iteratee

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D20533

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@270477 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm