[smartmontools-support] memory corruption problem on NetBSD

[Alexander Nasonov]

netbsd_smart_interface::get_dev_names() doesn't return a failure
early when no devices match a prefix (n == 0) and leads to a memory
corruption later. The patch below fixes this problem.

-- 
Alex

--- os_netbsd.cpp.orig	2018-09-16 15:03:22.000000000 +0000
+++ os_netbsd.cpp
@@ -603,6 +603,9 @@ int netbsd_smart_interface::get_dev_name
     n++;
   }
 
+  if (n == 0)
+    return -1;
+
   char ** tmp = (char **)realloc(mp, n * (sizeof(char *)));
   if (NULL == tmp) {
     pout("Out of memory constructing scan device list\n");