pgsql: Change predecence of phrase operator.

Change predecence of phrase operator.

<-> operator now have higher predecence than & (AND) operator. This change
was motivated by unexpected difference of similar queries:
'a & b <-> c'::tsquery and 'b <-> c & a'. Before first query means
(a & b) <-> c and second one - '(b <-> c) & a', now phrase operator evaluates
first.

Per suggestion from Tom Lane 32260.1465402409@sss.pgh.pa.us

Branch
------
master

Details
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http://git.postgresql.org/pg/commitdiff/6734a1cacd44f5b731933cbc93182b135b167d0c

Modified Files
--------------
src/backend/utils/adt/tsquery.c         | 114 +++++++++++++++-----------------
src/backend/utils/adt/tsquery_cleanup.c |  17 ++++-
src/include/tsearch/ts_type.h           |  16 +----
src/test/regress/expected/tsdicts.out   |  12 ++--
src/test/regress/expected/tsearch.out   |  18 ++---
src/test/regress/expected/tstypes.out   |  78 +++++++++++-----------
6 files changed, 121 insertions(+), 134 deletions(-)