llvm-objdump: Use help of CFG to print assembly when --cfg is passed.
llvm-objdump: Use help of CFG to print assembly when --cfg is passed.

This way we can avoid printing unreachable code (data).

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@137057 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/llvm,llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,dslab-epfl/asap,chubbymaggie/asap,llvm-mirror/llvm,dslab-epfl/asap,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm,dslab-epfl/asap,chubbymaggie/asap,dslab-epfl/asap,llvm-mirror/llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,chubbymaggie/asap,dslab-epfl/asap,apple/swift-llvm,chubbymaggie/asap,GPUOpen-Drivers/llvm,chubbymaggie/asap,GPUOpen-Drivers/llvm,dslab-epfl/asap,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,dslab-epfl/asap,chubbymaggie/asap,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm