Add option for disabling allocation from the packet zone

sys/conf/options

@@ -127,6 +127,7 @@ MUTEX_WAKE_ALL
 NO_ADAPTIVE_MUTEXES	opt_adaptive_mutexes.h
 NO_ADAPTIVE_RWLOCKS
 NSWBUF_MIN	opt_swap.h
+MBUF_PACKET_ZONE_DISABLE	opt_global.h
 PANIC_REBOOT_WAIT_TIME	opt_panic.h
 PPC_DEBUG	opt_ppc.h
 PPC_PROBE_CHIPSET opt_ppc.h

sys/sys/mbuf.h

@@ -451,6 +451,7 @@ m_gethdr(int how, short type)
 	return ((struct mbuf *)(uma_zalloc_arg(zone_mbuf, &args, how)));
 }
 
+#ifndef MBUF_PACKET_ZONE_DISABLE	
 static __inline struct mbuf *
 m_getcl(int how, short type, int flags)
 {
@@ -460,6 +461,9 @@ m_getcl(int how, short type, int flags)
 	args.type = type;
 	return ((struct mbuf *)(uma_zalloc_arg(zone_pack, &args, how)));
 }
+#else
+#define m_getcl(how, type, flags) m_getjcl(how, type, flags, MCLBYTES)
+#endif
 
 /*
  * m_getjcl() returns an mbuf with a cluster of the specified size attached.