Print basic block numbers in live interval debug output. Since the rest of the

Print basic block numbers in live interval debug output. Since the rest of the
debug output is showing machine instructions, the IR-level basic block names
aren't very meaningful, and because multiple machine basic blocks may be
derived from one IR-level BB, they're also not unique.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@102960 91177308-0d34-0410-b5e6-96231b3b80d8