AttributeSet::get(): Fix a valgrind error. It doesn't affect actual behavior, though.

Don't touch I->first on the end iterator, I == E!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173804 91177308-0d34-0410-b5e6-96231b3b80d8

lib/IR/Attributes.cpp

@@ -455,7 +455,7 @@ AttributeSet AttributeSet::get(LLVMContext &C,
          E = Attrs.end(); I != E; ) {
     unsigned Index = I->first;
     SmallVector<Attribute, 4> AttrVec;
-    while (I->first == Index && I != E) {
+    while (I != E && I->first == Index) {
       AttrVec.push_back(I->second);
       ++I;
     }