Change argument type of pq_sendbytes from char * to void *
This is a follow-up to
1f605b82ba66ece8b421b10d41094dd2e3c0c48b. It
allows getting rid of further casts at call sites.
Reviewed-by: Corey Huinker <corey.huinker@gmail.com>
Discussion: https://www.postgresql.org/message-id/
783a4edb-84f9-6df2-7470-
2ef5ccc6607a@enterprisedb.com