Fix build broken by r323641

The call to ScopedPrinter::printNumber with size_t argument was
ambiguous (I think) on 32-bit builds. Explicitly cast to a 64-bit int to
avoid this.

llvm-svn: 323642
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp b/llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp
index 3c7dc98..203f884 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp
@@ -201,7 +201,7 @@
   Hdr.dump(W);
 
   W.printNumber("DIE offset base", HdrData.DIEOffsetBase);
-  W.printNumber("Number of atoms", HdrData.Atoms.size());
+  W.printNumber("Number of atoms", uint64_t(HdrData.Atoms.size()));
   SmallVector<DWARFFormValue, 3> AtomForms;
   {
     ListScope AtomsScope(W, "Atoms");