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

Author: varungandhi-apple

include/swift/AST/ModuleLoader.h

@@ -22,7 +22,6 @@
 #include "swift/Basic/Located.h"
 #include "swift/Basic/SourceLoc.h"
 #include "llvm/ADT/SetVector.h"
-#include "llvm/ADT/StringSet.h"
 #include "llvm/ADT/TinyPtrVector.h"
 #include "swift/AST/ModuleDependencies.h"
 

include/swift/Basic/OutputFileMap.h

@@ -17,7 +17,6 @@
 #include "swift/Basic/LLVM.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/StringMap.h"
-#include "llvm/ADT/StringSet.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/SourceMgr.h"

include/swift/Driver/FineGrainedDependencyDriverGraph.h

@@ -23,7 +23,6 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
-#include "llvm/ADT/StringSet.h"
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/PointerLikeTypeTraits.h"