Check if STACK is defined before using the stack(9).

PR: 227446
Reported by: emaste
Approved by: ken

sys/dev/ocs_fc/ocs_os.c

@@ -37,6 +37,7 @@
  */
 
 #include "ocs.h"
+#include "opt_stack.h"
 #include <sys/sysctl.h>
 #include <sys/malloc.h>
 #include <sys/linker.h>		/* for debug of memory allocations */
@@ -855,11 +856,13 @@ void ocs_intr_enable(ocs_os_handle_t os)
 
 void ocs_print_stack(void)
 {
+#if defined(STACK)
 	struct stack st;
 
 	stack_zero(&st);
 	stack_save(&st);
 	stack_print(&st);
+#endif
 }
 
 void ocs_abort(void)