[spirv] Removed unused headers.

tools/clang/include/clang/SPIRV/SpirvModule.h

@@ -12,7 +12,6 @@
 #include <vector>
 
 #include "clang/SPIRV/SpirvInstruction.h"
-#include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/SmallVector.h"
 
 namespace clang {

tools/clang/lib/SPIRV/SpirvEmitter.h

@@ -32,7 +32,6 @@
 #include "clang/SPIRV/SpirvBuilder.h"
 #include "clang/SPIRV/SpirvContext.h"
 #include "llvm/ADT/STLExtras.h"
-#include "llvm/ADT/SetVector.h"
 
 #include "DeclResultIdMapper.h"
 #include "SpirvEvalInfo.h"