rpm: process i18nstring header types

[urbanchef]

SUMMARY, DESCRITPTION and GROUP header entry values were None. The fields are RPM_I18NSTRING_TYPE types (type == 9).

tag, type, offset, count
(1004, 9, 23, 1)
(1005, 9, 50, 1)

SUMMARY: None
DESCRIPTION: None
GROUP: None