[CodeView] Initialize column-end to zero

CodeView, unlike DWARF, can associate code with a range of columns.
However, LLVM can only represent a single column position internally.

We used to claim that the end column and start column were the same
which yielded less than satisfactory results: we would stop printing at
the _beginning_ of the source expression!  Instead, mark the column-end
as 'zero' to indicate that we don't have one (as per the documentation
for IDiaLineNumber::get_lineNumberEnd).

llvm-svn: 257528
diff --git a/llvm/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp b/llvm/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp
index c2c0f84..52116ce 100644
--- a/llvm/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp
@@ -283,7 +283,7 @@
          ColSegI != ColSegEnd; ++ColSegI) {
       unsigned ColumnNumber = InstrInfo[FI.Instrs[ColSegI]].ColumnNumber;
       Asm->EmitInt16(ColumnNumber); // Start column
-      Asm->EmitInt16(ColumnNumber); // End column
+      Asm->EmitInt16(0);            // End column
     }
     Asm->OutStreamer->EmitLabel(FileSegmentEnd);
   };