pgsql: Fix psql \d commands to behave properly when a pattern using

Log Message:
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Fix psql \d commands to behave properly when a pattern using regex | is given.
Formerly they'd emit '^foo|bar$' which is wrong because the anchors are
parsed as part of the alternatives; must emit '^(foo|bar)$' to get expected
behavior.  Same as bug found previously in similar_escape().  Already fixed
in HEAD, this is just back-porting the part of that patch that was a bug fix.

Tags:
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REL7_4_STABLE

Modified Files:
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    pgsql/src/bin/psql:
        describe.c (r1.87.2.2 -> r1.87.2.3)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/describe.c.diff?r1=1.87.2.2&r2=1.87.2.3)