Add a basic-block autovectorization pass.

This is the initial checkin of the basic-block autovectorization pass along with some supporting vectorization infrastructure.
Special thanks to everyone who helped review this code over the last several months (especially Tobias Grosser).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149468 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Transforms/IPO/PassManagerBuilder.h

@@ -99,6 +99,7 @@ public:
   bool DisableSimplifyLibCalls;
   bool DisableUnitAtATime;
   bool DisableUnrollLoops;
+  bool Vectorize;
 
 private:
   /// ExtensionList - This is list of all of the extensions that are registered.