Dwarf: use utostr on CUID to append to SmallString.

We used to do "SmallString += CUID", which is incorrect, since CUID will
be truncated to a char.

rdar://problem/13573833


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178941 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index d3cb4f9..8bd9feb 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -643,7 +643,7 @@
 
   // We look up the CUID/file/dir by concatenating them with a zero byte.
   SmallString<128> NamePair;
-  NamePair += CUID;
+  NamePair += utostr(CUID);
   NamePair += '\0';
   NamePair += DirName;
   NamePair += '\0'; // Zero bytes are not allowed in paths.