[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.

llvm-svn: 349403
diff --git a/llvm/lib/MC/MCCodeView.cpp b/llvm/lib/MC/MCCodeView.cpp
index 234b43e..978ac78 100644
--- a/llvm/lib/MC/MCCodeView.cpp
+++ b/llvm/lib/MC/MCCodeView.cpp
@@ -432,13 +432,13 @@
                                   OS.getCurrentSectionOnly());
 }
 
-void CodeViewContext::emitDefRange(
+MCFragment *CodeViewContext::emitDefRange(
     MCObjectStreamer &OS,
     ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
     StringRef FixedSizePortion) {
   // Create and insert a fragment into the current section that will be encoded
   // later.
-  new MCCVDefRangeFragment(Ranges, FixedSizePortion,
+  return new MCCVDefRangeFragment(Ranges, FixedSizePortion,
                            OS.getCurrentSectionOnly());
 }