[VPlan] Remove unused forward declarations. NFC.

Move VPlan.h include from VPlanVerifier.h down to VPlanVerifier.cpp

llvm/lib/Transforms/Vectorize/LoopVectorizationPlanner.h

@@ -31,6 +31,8 @@
 
 namespace llvm {
 
+class LoopVectorizationLegality;
+class LoopVectorizationCostModel;
 class PredicatedScalarEvolution;
 
 /// VPlan-based builder utility analogous to IRBuilder.

llvm/lib/Transforms/Vectorize/VPRecipeBuilder.h

@@ -18,7 +18,6 @@ namespace llvm {
 
 class LoopVectorizationLegality;
 class LoopVectorizationCostModel;
-class TargetTransformInfo;
 class TargetLibraryInfo;
 
 /// Helper class to create VPRecipies from IR instructions.

llvm/lib/Transforms/Vectorize/VPlan.h

@@ -48,8 +48,6 @@
 
 namespace llvm {
 
-class LoopVectorizationLegality;
-class LoopVectorizationCostModel;
 class BasicBlock;
 class DominatorTree;
 class InnerLoopVectorizer;
@@ -59,6 +57,7 @@ class raw_ostream;
 class Value;
 class VPBasicBlock;
 class VPRegionBlock;
+class VPSlotTracker;
 class VPlan;
 class VPlanSlp;
 
@@ -1501,7 +1500,6 @@ struct GraphTraits<Inverse<VPRegionBlock *>>
   }
 };
 
-class VPSlotTracker;
 /// VPlan models a candidate for vectorization, encoding various decisions take
 /// to produce efficient output IR, including which branches, basic-blocks and
 /// output IR instructions to generate, and their cost. VPlan holds a

llvm/lib/Transforms/Vectorize/VPlanVerifier.cpp

@@ -13,6 +13,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "VPlanVerifier.h"
+#include "VPlan.h"
 #include "llvm/ADT/DepthFirstIterator.h"
 #include "llvm/Support/CommandLine.h"
 

llvm/lib/Transforms/Vectorize/VPlanVerifier.h

@@ -24,9 +24,8 @@
 #ifndef LLVM_TRANSFORMS_VECTORIZE_VPLANVERIFIER_H
 #define LLVM_TRANSFORMS_VECTORIZE_VPLANVERIFIER_H
 
-#include "VPlan.h"
-
 namespace llvm {
+class VPRegionBlock;
 
 /// Struct with utility functions that can be used to check the consistency and
 /// invariants of a VPlan, including the components of its H-CFG.