proc-parse: Rework error paths

On error paths we don't explicitly close procfile.

CID 996191 (#5 of 6): Resource leak (RESOURCE_LEAK)
22. leaked_storage: Variable "f" going out of scope leaks the storage it points to.

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