object_classes[] provided unnecessary indirection between catalog OIDs
and the enum ObjectClass when calling add_object_address(). This array
has been originally introduced in 30ec31604d5 and was useful because not
all relation OIDs were compile-time constants back then, which has not
been the case for a long time now for all the elements of ObjectClass.
This commit removes object_classes[], switching to the catalog OIDs
when calling add_object_address(). This shaves some code while saving
in maintenance because it was necessary to maintain the enum ObjectClass
and the array in sync when adding new object types.
Reported-by: Jeff Davis
Author: Jelte Fennema-Nio
Reviewed-by: Jian He, Michael Paquier
Discussion: https://postgr.es/m/CAGECzQT3caUbcCcszNewCCmMbCuyP7XNAm60J3ybd6PN5kH2Dw@mail.gmail.com
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