Fix alignment issue.

The original code was taken from netlink's manpage, which is buggy.
The buffer might not be aligned to struct nlmsghdr pointers.

kernel_netlink.c

@@ -315,7 +315,7 @@ netlink_read(struct netlink *nl, struct netlink *nl_ignore, int answer,
     int done = 0;
     int skip = 0;
 
-    char buf[8192];
+    struct nlmsghdr buf[8192/sizeof(struct nlmsghdr)];
 
     memset(&nladdr, 0, sizeof(nladdr));
     nladdr.nl_family = AF_NETLINK;