[NFC] Remove redundant includes for llvm/ADT/BitVector.h.

Author: varungandhi-apple

include/swift/SILOptimizer/Analysis/ARCAnalysis.h

@@ -20,7 +20,6 @@
 #include "swift/SILOptimizer/Analysis/AliasAnalysis.h"
 #include "swift/SILOptimizer/Analysis/PostOrderAnalysis.h"
 #include "swift/SILOptimizer/Analysis/RCIdentityAnalysis.h"
-#include "llvm/ADT/BitVector.h"
 #include "llvm/ADT/MapVector.h"
 #include "llvm/ADT/TinyPtrVector.h"