openbsd_network: Add a real implementation of MCLGETL.

The old alias had a number of shortcomings which made it not match
OpenBSD and thus special-casing had to be used in drivers. The new
version should match OpenBSD's semantics precisely.

src/add-ons/kernel/drivers/network/wlan/iaxwifi200/dev/pci/if_iwx.c

@@ -5681,11 +5681,7 @@ iwx_send_cmd(struct iwx_softc *sc, struct iwx_host_cmd *hcmd)
 			err = EINVAL;
 			goto out;
 		}
-#ifdef __FreeBSD_version
-		m = m_getjcl(M_NOWAIT, MT_DATA, M_PKTHDR, IWX_RBUF_SIZE);
-#else
 		m = MCLGETL(NULL, M_DONTWAIT, totlen);
-#endif
 		if (m == NULL) {
 			printf("%s: could not get fw cmd mbuf (%zd bytes)\n",
 			    DEVNAME(sc), totlen);

src/add-ons/kernel/drivers/network/wlan/idualwifi7260/dev/pci/if_iwm.c

@@ -6366,11 +6366,7 @@ iwm_send_cmd(struct iwm_softc *sc, struct iwm_host_cmd *hcmd)
 			err = EINVAL;
 			goto out;
 		}
-#ifdef __FreeBSD_version
-		m = m_getjcl(M_NOWAIT, MT_DATA, M_PKTHDR, IWM_RBUF_SIZE);
-#else
 		m = MCLGETL(NULL, M_DONTWAIT, totlen);
-#endif
 		if (m == NULL) {
 			printf("%s: could not get fw cmd mbuf (%zd bytes)\n",
 			    DEVNAME(sc), totlen);

src/libs/compat/openbsd_network/compat/sys/mbuf.h

@@ -27,8 +27,16 @@
 
 #define MAXMCLBYTES MJUM16BYTES
 
-#define MCLGETL m_cljget
 
+static struct mbuf*
+MCLGETL(struct mbuf* m, int how, int size)
+{
+	if (m == NULL)
+		return m_get2(size, how, MT_DATA, M_PKTHDR);
+
+	m_cljget(m, how, size);
+	return m;
+}
 
 static int
 m_dup_pkthdr_openbsd(struct mbuf* to, const struct mbuf* from, int how)