Improve possible performance regression
Commit
ce62f2f2a0a introduced calls to GetIndexAmRoutineByAmId() in
lsyscache.c functions. This call is a bit more expensive than a
simple syscache lookup. So rearrange the nesting so that we call that
one last and do the cheaper checks first.
Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/flat/E1tngY6-0000UL-2n%40gemulon.postgresql.org