Fix non-unity build

#rb none


#ROBOMERGE-SOURCE: CL 9148007 via CL 9148028
#ROBOMERGE-BOT: (v443-9013191)

[CL 9148040 by thomas sarkanen in Main branch]

Engine/Source/Editor/AnimGraph/Classes/AnimationGraphSchema.h

@@ -12,6 +12,8 @@
 
 class FMenuBuilder;
 class UAnimationAsset;
+class UAnimBlueprint;
+struct FBPInterfaceDescription;
 
 UCLASS(MinimalAPI)
 class UAnimationGraphSchema : public UEdGraphSchema_K2