pgsql: Fix tsvectorout() and tsqueryout() to escape backslesh, add test

Log Message:
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Fix tsvectorout() and tsqueryout() to escape backslesh, add test of that.
Patch by Bruce Momjian <bruce@momjian.us>

Backpatch is needed, but it's impossible to apply it directly

Modified Files:
--------------
    pgsql/src/backend/utils/adt:
        tsquery.c (r1.10 -> r1.11)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/tsquery.c?r1=1.10&r2=1.11)
        tsvector.c (r1.8 -> r1.9)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/tsvector.c?r1=1.8&r2=1.9)
    pgsql/src/test/regress/expected:
        tstypes.out (r1.2 -> r1.3)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/tstypes.out?r1=1.2&r2=1.3)
    pgsql/src/test/regress/sql:
        tstypes.sql (r1.2 -> r1.3)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/tstypes.sql?r1=1.2&r2=1.3)