proc_parse: Borrow vmi iif there is file referenced

Otherwise we migh propagate previous vfi status
to vmas which actually don't match.

 | (00.005471) 0x2b79227d6000-0x2b79227d8000 (8K) prot 0x5 flags 0x22 off 0 reg vdso ap  shmid: 0
 | (00.005473) 0x2b79227d8000-0x2b79227da000 (8K) prot 0x3 flags 0x22 off 0 reg vdso ap  shmid: 0
 | (00.005475) 0x2b79227f1000-0x2b79227f2000 (4K) prot 0x3 flags 0x22 off 0 reg vdso ap  shmid: 0
 | (00.005476) 0x2b79227f2000-0x2b79227f4000 (8K) prot 0x3 flags 0x22 off 0 reg vdso ap  shmid: 0

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