Fix recent cpluspluscheck issue in selfuncs.h.

Fix selfuncs.h cpluspluscheck complaint, without reintroducing a
parameter name inconsistency (restore the original declaration names,
and then make corresponding function definitions consistent with that).

Oversight in commit a601366a.

Author: Peter Geoghegan <pg@bowt.ie>
Reported-By: Andres Freund <andres@anarazel.de>

src/backend/utils/adt/selfuncs.c

@@ -290,7 +290,7 @@ eqsel_internal(PG_FUNCTION_ARGS, bool negate)
  * This is exported so that some other estimation functions can use it.
  */
 double
-var_eq_const(VariableStatData *vardata, Oid operator, Oid collation,
+var_eq_const(VariableStatData *vardata, Oid oproid, Oid collation,
 			 Datum constval, bool constisnull,
 			 bool varonleft, bool negate)
 {
@@ -331,7 +331,7 @@ var_eq_const(VariableStatData *vardata, Oid operator, Oid collation,
 	}
 	else if (HeapTupleIsValid(vardata->statsTuple) &&
 			 statistic_proc_security_check(vardata,
-										   (opfuncoid = get_opcode(operator))))
+										   (opfuncoid = get_opcode(oproid))))
 	{
 		AttStatsSlot sslot;
 		bool		match = false;
@@ -461,7 +461,7 @@ var_eq_const(VariableStatData *vardata, Oid operator, Oid collation,
  * This is exported so that some other estimation functions can use it.
  */
 double
-var_eq_non_const(VariableStatData *vardata, Oid operator, Oid collation,
+var_eq_non_const(VariableStatData *vardata, Oid oproid, Oid collation,
 				 Node *other,
 				 bool varonleft, bool negate)
 {

src/include/utils/selfuncs.h

@@ -181,11 +181,11 @@ extern double ineq_histogram_selectivity(PlannerInfo *root,
 										 Oid collation,
 										 Datum constval, Oid consttype);
 extern double var_eq_const(VariableStatData *vardata,
-						   Oid operator, Oid collation,
+						   Oid oproid, Oid collation,
 						   Datum constval, bool constisnull,
 						   bool varonleft, bool negate);
 extern double var_eq_non_const(VariableStatData *vardata,
-							   Oid operator, Oid collation,
+							   Oid oproid, Oid collation,
 							   Node *other,
 							   bool varonleft, bool negate);