Fix typo in comment.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@3773 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/llvm/Pass.h b/include/llvm/Pass.h
index d2cbb7e..f237b1a 100644
--- a/include/llvm/Pass.h
+++ b/include/llvm/Pass.h
@@ -247,7 +247,7 @@
 ///      instruction at a time.
 ///   2. Optimizations do not modify the CFG of the contained function, or any
 ///      other basic block in the function.
-///   3. Optimizations conform to all of the contstraints of FunctionPass's.
+///   3. Optimizations conform to all of the constraints of FunctionPass's.
 ///
 struct BasicBlockPass : public FunctionPass {
   /// doInitialization - Virtual method overridden by subclasses to do