pgsql: When using C-string lookup keys in a dynahash.c hash table, use

Log Message:
-----------
When using C-string lookup keys in a dynahash.c hash table, use strncpy()
not memcpy() to copy the offered key into the hash table during HASH_ENTER.
This avoids possible core dump if the passed key is located very near the
end of memory. Per report from Stefan Kaltenbrunner.

Tags:
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REL8_0_STABLE

Modified Files:
--------------
pgsql/src/backend/utils/hash:
dynahash.c (r1.58 -> r1.58.4.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/hash/dynahash.c.diff?r1=1.58&r2=1.58.4.1)
pgsql/src/include/utils:
hsearch.h (r1.34 -> r1.34.4.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/hsearch.h.diff?r1=1.34&r2=1.34.4.1)