pgsql: Avoid possibly accessing off the end of memory in SJIS2004 conve

Avoid possibly accessing off the end of memory in SJIS2004 conversion.

The code in shift_jis_20042euc_jis_2004() would fetch two bytes even when
only one remained in the string. Since conversion functions aren't
supposed to assume null-terminated input, this poses a small risk of
fetching past the end of memory and incurring SIGSEGV. No such crash has
been identified in the field, but we've certainly seen the equivalent
happen in other code paths, so patch this one all the way back.

Report and patch by Noah Misch.

Branch
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REL9_0_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/d5e429b128b0e222f9458a7880427a60da065fa3

Modified Files
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.../euc2004_sjis2004/euc2004_sjis2004.c | 8 ++++----
1 files changed, 4 insertions(+), 4 deletions(-)