pgsql: Create index on srt table in citext regression tests.

Create index on srt table in citext regression tests.

Comments and the tests make clear that the intent is to test with
and without an index, but there was no index.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/a49d0b75ce41a5480777f0957d5119cb2f393414

Modified Files
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contrib/citext/expected/citext.out   |    1 +
contrib/citext/expected/citext_1.out |    1 +
contrib/citext/sql/citext.sql        |    2 ++
3 files changed, 4 insertions(+)