simplify compatibility check for fix reax/c/bonds with pair styles

src/USER-REAXC/fix_reaxc_bonds.cpp

@@ -121,12 +121,9 @@ void FixReaxCBonds::setup(int vflag)
 
 void FixReaxCBonds::init()
 {
-  reaxc = (PairReaxC *) force->pair_match("reax/c",1);
-  if (reaxc == NULL)
-    reaxc = (PairReaxC *) force->pair_match("reax/c/kk",1);
-
+  reaxc = (PairReaxC *) force->pair_match("reax/c",0);
   if (reaxc == NULL) error->all(FLERR,"Cannot use fix reax/c/bonds without "
-                  "pair_style reax/c");
+                                "pair_style reax/c, reax/c/kk, or reax/c/omp");
 
 }