pgsql: Fix Windows shell argument quoting.

Fix Windows shell argument quoting.

The incorrect quoting may have permitted arbitrary command execution.
At a minimum, it gave broader control over the command line to actors
supposed to have control over a single argument.  Back-patch to 9.1 (all
supported versions).

Security: CVE-2016-5424

Branch
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REL9_2_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/4837155292f67f10576f3d7204ffd5379bbe3a7b

Modified Files
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src/bin/pg_dump/pg_dumpall.c | 52 +++++++++++++++++++++++++++++++++++++++-----
1 file changed, 47 insertions(+), 5 deletions(-)