pgsql: Sort out paired double quotes in \connect, \password and \crosst

Sort out paired double quotes in \connect, \password and \crosstabview.

In arguments, these meta-commands wrongly treated each pair as closing
the double quoted string.  Make the behavior match the documentation.
This is a compatibility break, but I more expect to find software with
untested reliance on the documented behavior than software reliant on
today's behavior.  Back-patch to 9.1 (all supported versions).

Reviewed by Tom Lane and Peter Eisentraut.

Security: CVE-2016-5424

Branch
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REL9_4_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/fed83cdac44da06915f9cf5926a282848841f7c1

Modified Files
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src/bin/psql/psqlscan.l | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)