address some issues flagged by static code analysis

src/APIP/atom_vec_apip.h

@@ -28,7 +28,7 @@ class AtomVecApip : public AtomVec {
  public:
   AtomVecApip(class LAMMPS *);
 
-  void grow_pointers();
+  void grow_pointers() override;
 
   void force_clear(int, size_t) override;
   void data_atom_post(int) override;

src/APIP/fix_lambda_apip.cpp

@@ -26,6 +26,8 @@
 #include "memory.h"
 #include "modify.h"
 #include "pair.h"
+#include "pair_lambda_input_apip.h"
+#include "pair_lambda_zone_apip.h"
 #include "update.h"
 
 using namespace LAMMPS_NS;

src/APIP/fix_lambda_apip.h

@@ -24,8 +24,6 @@ FixStyle(lambda/apip,FixLambdaAPIP);
 #define LMP_FIX_LAMBDA_APIP_H
 
 #include "fix.h"
-#include "pair_lambda_input_apip.h"
-#include "pair_lambda_zone_apip.h"
 
 namespace LAMMPS_NS {