Fix a typo 'iff' => 'if'

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164767 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/BreakCriticalEdges.cpp b/lib/Transforms/Utils/BreakCriticalEdges.cpp
index 6b04e3d..2a604b6 100644
--- a/lib/Transforms/Utils/BreakCriticalEdges.cpp
+++ b/lib/Transforms/Utils/BreakCriticalEdges.cpp
@@ -104,7 +104,7 @@
     return I != E;
 
   // If AllowIdenticalEdges is true, then we allow this edge to be considered
-  // non-critical iff all preds come from TI's block.
+  // non-critical if all preds come from TI's block.
   while (I != E) {
     const BasicBlock *P = *I;
     if (P != FirstPred)