pkg/report: support new caller info

[dvyukov]

Kernel patch "printk: inject caller information into the body of message":
http://lkml.iu.edu/hypermail/linux/kernel/1805.1/03326.html
It adds task/cpu ids into kernel output and should help to fight "corrupted" reports:

[  229.345646] (T34) WARNING: CPU: 2 PID: 34 at net/ipv6/xfrm6_tunnel.c:348 xfrm6_tunnel_net_exit+0x2df/0x510
[  229.347512] (T30251) bond0: Enslaving bond_slave_1 as an active interface with an up link
[  229.347599] (T34) Kernel panic - not syncing: panic_on_warn set ...
[  229.347599] 
[  229.350663] (T34) CPU: 2 PID: 34 Comm: kworker/u12:1 Not tainted 4.17.0-rc4+ #2
[  229.351959] (T34) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
[  229.353717] (T34) Workqueue: netns cleanup_net
[  229.354548] (T34) Call Trace:
[  229.355119] (T34)  dump_stack+0x1b9/0x294
[  229.355875] (T34)  ? dump_stack_print_info.cold.2+0x52/0x52
[  229.356916] (T34)  ? xfrm6_tunnel_net_exit+0x2b0/0x510

Once the patch is merged, we should support this output in pkg/report.

[dvyukov]

This is not committed yet.

[dvyukov]

The patch was merged into linux-next:
https://groups.google.com/d/msg/syzkaller/xEDUgkgFvL8/d5bBS3BJBwAJ