sbmask function should be flagged as const indicating no side effects

src/compute.h

@@ -152,7 +152,7 @@ class Compute : protected Pointers {
   double **vbiasall;           // stored velocity bias for all atoms
   int maxbias;                 // size of vbiasall array
 
-  inline int sbmask(int j) {
+  inline int sbmask(int j) const {
     return j >> SBBITS & 3;
   }
 

src/create_bonds.h

@@ -30,7 +30,7 @@ class CreateBonds : protected Pointers {
   void command(int, char **);
 
  private:
-  inline int sbmask(int j) {
+  inline int sbmask(int j) const {
     return j >> SBBITS & 3;
   }
 };

src/delete_atoms.h

@@ -45,7 +45,7 @@ class DeleteAtoms : protected Pointers {
   void recount_topology();
   void options(int, char **);
 
-  inline int sbmask(int j) {
+  inline int sbmask(int j) const {
     return j >> SBBITS & 3;
   }
 

src/pair.h

@@ -245,7 +245,7 @@ class Pair : protected Pointers {
     ubuf(int arg) : i(arg) {}
   };
 
-  inline int sbmask(int j) {
+  inline int sbmask(int j) const {
     return j >> SBBITS & 3;
   }
 };