cr: Support rlimits

Dump the with "new" prlimit syscall that works on arbitrary pid.

Restore is done in restorer _after_ mappings mixup and _before_
caps drop to make it set any max value.

The RLIM_INFINITY is handled explicitly to help future 64<->32
bits migration.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>