show: protobuf -- Fix rendering of repeated messages

Repeated custom entries are presented as an array
of pointers in the memory, so once we fetch the
first entry we are to continue iterating pointers
instead.

Before

	| vmas: {
	|         start: 0x00000000400000
	|         end: 0x00000000406000
	|         pgoff: 0000000000000000
	|         shmid: 0x0000000000000b
	|         prot: 0x5
	|         flags: 0x2
	|         status: 0x41
	|         fd: 0xffffffffffffffff
	| }
	| :{
	|         start: 0x00000000462d00
	|         end: 0000000000000000
	|         pgoff: 0000000000000000
	|         shmid: 0x00000000605000
	|         prot: 0x606000
	|         flags: 0
	|         status: 0x5000
	|         fd: 0x0000000000000b
	|         madv: 0x00000000000041
	| }

After

	| vmas: {
	|         start: 0x00000000400000
	|         end: 0x00000000406000
	|         pgoff: 0000000000000000
	|         shmid: 0x0000000000000b
	|         prot: 0x5
	|         flags: 0x2
	|         status: 0x41
	|         fd: 0xffffffffffffffff
	| }
	| :{
	|         start: 0x00000000605000
	|         end: 0x00000000606000
	|         pgoff: 0x00000000005000
	|         shmid: 0x0000000000000b
	|         prot: 0x1
	|         flags: 0x2
	|         status: 0x41
	|         fd: 0xffffffffffffffff
	| }

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>