pgsql: Inserting 5 characters into char(10) does not produce 5 padding

Log Message:
-----------
Inserting 5 characters into char(10) does not produce 5 padding spaces
if they are two-byte multibyte characters. Same thing can be happen
if octet_length(multibyte_chars) == n where n is char(n).
Long standing bug since 7.3 days. Per report and fix from Yoshiyuki Asaba.

Tags:
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REL8_0_STABLE

Modified Files:
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    pgsql/src/backend/parser:
        parse_expr.c (r1.179 -> r1.179.4.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_expr.c.diff?r1=1.179&r2=1.179.4.1)