pgsql: tableam: Allow choice of toast AM.

tableam: Allow choice of toast AM.

Previously, the toast table had to be implemented by the same AM that
was used for the main table, which was bad, because the detoasting
code won't work with anything but heap. This commit doesn't fix the
latter problem, although there's another patch coming which does,
but it does let you pick something that works (i.e. heap, right now).

Patch by me, reviewed by Andres Freund.

Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/83322e38da1aa054e1b144cb37e6074a86854199

Modified Files
--------------
src/backend/access/heap/heapam_handler.c | 10 ++++++++++
src/backend/catalog/toasting.c | 2 +-
src/include/access/tableam.h | 17 +++++++++++++++++
3 files changed, 28 insertions(+), 1 deletion(-)