pgsql: Improve "invalid byte sequence for encoding" message

Improve "invalid byte sequence for encoding" message

It used to say

ERROR:  invalid byte sequence for encoding "UTF8": 0xdb24

Change this to

ERROR:  invalid byte sequence for encoding "UTF8": 0xdb 0x24

to make it clear that this is a byte sequence and not a code point.

Also fix the adjacent "character has no equivalent" message that has
the same issue.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/a2a5ce68266d879c7acd292952adc376966622e0

Modified Files
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src/backend/utils/mb/wchar.c |   20 ++++++++++++++------
1 files changed, 14 insertions(+), 6 deletions(-)