Merge from x86:

r233961:

Fix interrupt load balancing regression, introduced in revision
222813, that left all un-pinned interrupts assigned to CPU 0.
In intr_shuffle_irqs(), remove CPU_SETOF() call that initialized
the "intr_cpus" cpuset to only contain CPU0.

This initialization is too late and nullifies the results of calls
to the intr_add_cpu() that occur much earlier in the boot process.

r234074 (partial):

The BSP is not added to the mask of valid target CPUs for interrupts.
Fix this by adding the BSP as an interrupt target directly in

r234105:

Fix !SMP build after r234074.

MFC after: 3 days

sys/sparc64/sparc64/intr_machdep.c

@@ -528,9 +528,6 @@ intr_shuffle_irqs(void *arg __unused)
 	struct intr_vector *iv;
 	int i;
 
-	/* The BSP is always a valid target. */
-	CPU_SETOF(0, &intr_cpus);
-
 	/* Don't bother on UP. */
 	if (mp_ncpus == 1)
 		return;

sys/sparc64/sparc64/machdep.c

@@ -196,6 +196,13 @@ cpu_startup(void *arg)
 		printf("machine: %s\n", sparc64_model);
 
 	cpu_identify(rdpr(ver), PCPU_GET(clock), curcpu);
+
+#ifdef SMP
+	/*
+	 * Add BSP as an interrupt target.
+	 */
+	intr_add_cpu(0);
+#endif
 }
 
 void