pgsql: Fix null-dereference crash in parse_xml_decl().

Fix null-dereference crash in parse_xml_decl().

parse_xml_decl's header comment says you can pass NULL for any unwanted
output parameter, but it failed to honor this contract for the "standalone"
flag. The only currently-affected caller is xml_recv, so the net effect is
that sending a binary XML value containing a standalone parameter in its
xml declaration would crash the backend. Per bug #6044 from Christopher
Dillard.

In passing, remove useless initializations of parse_xml_decl's output
parameters in xml_parse.

Back-patch to 8.3, where this code was introduced.

Branch
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REL8_4_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/d6a9e7a1e45a3569b3c3558b5817e78756224be2

Modified Files
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src/backend/utils/adt/xml.c | 10 ++++++----
1 files changed, 6 insertions(+), 4 deletions(-)