Fix operator typo in tablecmds.c

A bitwise operator was getting used on two bools in
ATAddCheckConstraint() to track if constraints should be merged or not
with the existing ones of a relation, though obviously this should use
a boolean OR operator.  This led to the same result, but let's be
clean.

Oversight in 074c5cf.

Author: Ranier Vilela
Reviewed-by: Justin Pryzby
Discussion: https://postgr.es/m/CAEudQAp2R2fbbi0OHHhv_n4=Ch0t1VtjObR9YMqtGKHJ+faUFQ@mail.gmail.com

src/backend/commands/tablecmds.c

@@ -8863,7 +8863,7 @@ ATAddCheckConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	 */
 	newcons = AddRelationNewConstraints(rel, NIL,
 										list_make1(copyObject(constr)),
-										recursing | is_readd,	/* allow_merge */
+										recursing || is_readd,	/* allow_merge */
 										!recursing, /* is_local */
 										is_readd,	/* is_internal */
 										NULL);	/* queryString not available