Unbreak Clang build after r191050: don't pass a StringRef to snprintf.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191062 91177308-0d34-0410-b5e6-96231b3b80d8

lib/DebugInfo/DWARFContext.cpp

@@ -135,8 +135,9 @@ void DWARFContext::dump(raw_ostream &OS, DIDumpType DumpType) {
         break;
       PubIndexEntryDescriptor desc(pubNames.getU8(&offset));
       OS << format("0x%8.8x ", dieRef)
-         << format("%-8s", dwarf::GDBIndexEntryLinkageString(desc.Linkage))
-         << ' ' << dwarf::GDBIndexEntryKindString(desc.Kind) << " \""
+         << format("%-8s", dwarf::GDBIndexEntryLinkageString(desc.Linkage)
+                               .str().c_str()) << ' '
+         << dwarf::GDBIndexEntryKindString(desc.Kind) << " \""
          << pubNames.getCStr(&offset) << "\"\n";
     }
   }