Use an unsigned type because there seems to be no reason for it to be signed.

llvm-svn: 222966
diff --git a/llvm/lib/TableGen/TGParser.cpp b/llvm/lib/TableGen/TGParser.cpp
index b6ed2e8..fbb4184 100644
--- a/llvm/lib/TableGen/TGParser.cpp
+++ b/llvm/lib/TableGen/TGParser.cpp
@@ -224,7 +224,7 @@
     if (AddValue(CurRec, SubMultiClass.RefRange.Start, SMCVals[i]))
       return true;
 
-  int newDefStart = CurMC->DefPrototypes.size();
+  unsigned newDefStart = CurMC->DefPrototypes.size();
 
   // Add all of the defs in the subclass into the current multiclass.
   for (MultiClass::RecordVector::const_iterator i = SMC->DefPrototypes.begin(),