Fix typos found by http://github.com/lyda/misspell-check

llvm-svn: 157885
diff --git a/llvm/lib/Transforms/Scalar/Reassociate.cpp b/llvm/lib/Transforms/Scalar/Reassociate.cpp
index 0da70b3..d036c66 100644
--- a/llvm/lib/Transforms/Scalar/Reassociate.cpp
+++ b/llvm/lib/Transforms/Scalar/Reassociate.cpp
@@ -1164,7 +1164,7 @@
       ++Count;
     if (Count == 1)
       continue;
-    // Move an even number of occurences to Factors.
+    // Move an even number of occurrences to Factors.
     Count &= ~1U;
     Idx -= Count;
     FactorPowerSum += Count;