Add boot_ncpus macro

For compatibility define boot_ncpus as num_online_cpus().

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

include/sys/sysmacros.h

@@ -78,6 +78,7 @@
 #define proc_pageout			NULL
 #define curproc				current
 #define max_ncpus			num_possible_cpus()
+#define boot_ncpus			num_online_cpus()
 #define CPU_SEQID			smp_processor_id()
 #define _NOTE(x)
 #define is_system_labeled()		0