pgsql: Fix cursor_to_xml in tableforest false mode

Fix cursor_to_xml in tableforest false mode

It only produced <row> elements but no wrapping <table> element.

By contrast, cursor_to_xmlschema produced a schema that is now correct
but did not previously match the XML data produced by cursor_to_xml.

In passing, also fix a minor misunderstanding about moving cursors in
the tests related to this.

Reported-by: filip(at)jirsak(dot)org
Based-on-patch-by: Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>

Branch
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REL9_5_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/9750a9583aacefbde15d9ed4ebfed84f1fb3aae8

Modified Files
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src/backend/utils/adt/xml.c | 13 +++++++
src/test/regress/expected/xmlmap.out | 64 +++++++++++++++++++++++++++-------
src/test/regress/expected/xmlmap_1.out | 6 +++-
src/test/regress/sql/xmlmap.sql | 3 +-
4 files changed, 71 insertions(+), 15 deletions(-)