Improve style of two code paths

In execGrouping.c, execTuplesMatchPrepare() was doing a memory
allocation that was not necessary when the number of columns was 0.
In foreign.c, pg_options_to_table() was assigning twice a variable to
the same value.

Author: Ranier Vilela
Discussion: https://postgr.es/m/CAEudQAqup0agbSzMjSLSTn=OANyCzxENF1+HrSYnr3WyZib7=Q@mail.gmail.com

Author: michaelpq

src/backend/executor/execGrouping.c

@@ -62,13 +62,15 @@ execTuplesMatchPrepare(TupleDesc desc,
 					   const Oid *collations,
 					   PlanState *parent)
 {
-	Oid		   *eqFunctions = (Oid *) palloc(numCols * sizeof(Oid));
+	Oid		   *eqFunctions;
 	int			i;
 	ExprState  *expr;
 
 	if (numCols == 0)
 		return NULL;
 
+	eqFunctions = (Oid *) palloc(numCols * sizeof(Oid));
+
 	/* lookup equality functions */
 	for (i = 0; i < numCols; i++)
 		eqFunctions[i] = get_opcode(eqOperators[i]);

src/backend/foreign/foreign.c

@@ -524,7 +524,7 @@ pg_options_to_table(PG_FUNCTION_ARGS)
 	Datum		array = PG_GETARG_DATUM(0);
 	ListCell   *cell;
 	List	   *options;
-	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	ReturnSetInfo *rsinfo;
 
 	options = untransformRelOptions(array);
 	rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;