Emit less labels for debug info and stop emitting .loc directives for DBG_VALUEs.

The .dot directives don't need labels, that is a leftover from when we created
line number info manually.

Instructions following a DBG_VALUE can share its label since the DBG_VALUE
doesn't produce any code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128284 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed