Attempting to fix the 64 bit bots.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211351 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/ADT/BitVector.h

@@ -34,7 +34,7 @@ class BitVector {
   unsigned Capacity;     // Size of allocated memory in BitWord.
 
 public:
-  typedef size_t size_type;
+  typedef unsigned size_type;
   // Encapsulation of a single bit.
   class reference {
     friend class BitVector;