pg_dump: Remove some unused return values.
getSchemaData() does not use the return values of many of its get*
helper functions because they store the data elsewhere. For
example, commit
92316a4582 introduced a separate hash table for
dumpable objects that said helper functions populate. This commit
changes these functions to return void and removes their "int *"
parameters that returned the number of objects found.
Reviewed-by: Neil Conway, Tom Lane, Daniel Gustafsson
Discussion: https://postgr.es/m/ZmCAtVaOrHpf31PJ%40nathan