SILOptimizer: Remove unnecessary #include of GenericSignatureBuilder.h

Author: slavapestov

lib/SILOptimizer/Mandatory/Differentiation.cpp

@@ -25,7 +25,6 @@
 #include "swift/AST/DiagnosticsSIL.h"
 #include "swift/AST/Expr.h"
 #include "swift/AST/GenericEnvironment.h"
-#include "swift/AST/GenericSignatureBuilder.h"
 #include "swift/AST/LazyResolver.h"
 #include "swift/AST/ParameterList.h"
 #include "swift/AST/SourceFile.h"