make friends for access to instance_me member

src/compute.h

@@ -19,6 +19,8 @@
 namespace LAMMPS_NS {
 
 class Compute : protected Pointers {
+  friend class Neighbor;
+
  public:
   // clang-format off
   enum {

src/fix.h

@@ -19,6 +19,8 @@
 namespace LAMMPS_NS {
 
 class Fix : protected Pointers {
+  friend class Neighbor;
+
  public:
   static int instance_total;    // # of Fix classes ever instantiated
 

src/pair.h

@@ -33,6 +33,7 @@ class Pair : protected Pointers {
   friend class PairHybridScaled;
   friend class ThrOMP;
   friend class Info;
+  friend class Neighbor;
 
  public:
   static int instance_total;    // # of Pair classes ever instantiated