pgsql: Don't downcase non-ascii identifier chars in multi-byte encoding

Don't downcase non-ascii identifier chars in multi-byte encodings.

Long-standing code has called tolower() on identifier character bytes
with the high bit set. This is clearly an error and produces junk output
when the encoding is multi-byte. This patch therefore restricts this
activity to cases where there is a character with the high bit set AND
the encoding is single-byte.

There have been numerous gripes about this, most recently from Martin
Schäfer.

Backpatch to all live releases.

Branch
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REL9_1_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/d7cb64aeb5a7e40f4ea75e60bba1d606ca06df7f

Modified Files
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src/backend/parser/scansup.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)