Revert 'Fix a typo 'iff' => 'if''. iff is an abreviation of if and only if. See: http://en.wikipedia.org/wiki/If_and_only_if Commit 164767

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164768 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/Interval.cpp b/lib/Analysis/Interval.cpp
index 125d42e..ca9cdca 100644
--- a/lib/Analysis/Interval.cpp
+++ b/lib/Analysis/Interval.cpp
@@ -27,7 +27,7 @@
 // isLoop - Find out if there is a back edge in this interval...
 //
 bool Interval::isLoop() const {
-  // There is a loop in this interval if one of the predecessors of the header
+  // There is a loop in this interval iff one of the predecessors of the header
   // node lives in the interval.
   for (::pred_iterator I = ::pred_begin(HeaderNode), E = ::pred_end(HeaderNode);
        I != E; ++I)