inspection: Correct fix for segfault if /etc/SuSE-release is an empty…

… file.

The test was the wrong way round.

See: CVE-2013-2124.

This fixes commit ae8bb84.

src/inspect-fs-unix.c

@@ -338,7 +338,7 @@ parse_suse_release (guestfs_h *g, struct inspect_fs *fs, const char *filename)
   if (lines == NULL)
     return -1;
 
-  if (lines[0] != NULL)
+  if (lines[0] == NULL)
     goto out;
 
   /* First line is dist release name */