[codeview] Flush labels before S_DEFRANGE* fragments

This was a pre-existing bug that could be triggered with assembly like
this:
  .p2align 2
  .LtmpN:
  .cv_def_range "..."

I noticed this when attempting to change clang to emit aligned symbol
records.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@349403 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed