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
------
REL9_1_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/f270a1611026616d1304d4623f7e7acd0d6c63d6

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