sshbuf_poke_u32
ASSERT_INT_EQ(sshbuf_poke_u32(p1, 0, 0xa1b2c3d4), 0);
ASSERT_INT_EQ(sshbuf_poke_u32(p1, 6, 0xa1b2c3d4), 0);
ASSERT_INT_EQ(sshbuf_poke_u32(p1, 7, 0xa1b2c3d4),
ASSERT_INT_EQ(sshbuf_poke_u32(p1, 10, 0xa1b2c3d4),
ASSERT_INT_EQ(sshbuf_poke_u32(p1, 1000, 0xa1b2c3d4),
int sshbuf_poke_u32(struct sshbuf *buf, size_t offset, u_int32_t val);