More dead code removal (using -Wunreachable-code)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148578 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/BranchFolding.cpp

@@ -483,8 +483,9 @@ BranchFolder::MergePotentialsElt::operator<(const MergePotentialsElt &o) const {
     // an object with itself.
 #ifndef _GLIBCXX_DEBUG
     llvm_unreachable("Predecessor appears twice");
-#endif
+#else
     return false;
+#endif
   }
 }