trim unneeded includes

src/compute_fragment_atom.cpp

@@ -21,9 +21,7 @@
 #include "atom_vec.h"
 #include "update.h"
 #include "modify.h"
-#include "neighbor.h"
 #include "force.h"
-#include "pair.h"
 #include "comm.h"
 #include "memory.h"
 #include "error.h"