pgsql: Check for GiST index tuples that don't fit on a page.

Check for GiST index tuples that don't fit on a page.

The page splitting code would go into infinite recursion if you try to
insert an index tuple that doesn't fit even on an empty page.

Per analysis and suggested fix by Andrew Gierth. Fixes bug #11555, reported
by Bryan Seitz (analysis happened over IRC). Backpatch to all supported
versions.

Branch
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REL9_0_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/f04b112d573be996099300c83054aa5564d2b520

Modified Files
--------------
src/backend/access/gist/gist.c |   17 +++++++++++++++++
1 file changed, 17 insertions(+)