dpkg: support config file overwrite options

dpkg: support config file overwrite options

function                                             old     new   delta
filter_rename_config                                   -     244    +244
static.dpkg_longopts                                   -     112    +112
dpkg_main                                           3901    3980     +79
unpack_package                                       515     587     +72
append_control_file_to_llist                           -      72     +72
data_extract_all_prefix                               88     116     +28
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(add/remove: 3/0 grow/shrink: 3/0 up/down: 607/0)             Total: 607 bytes

Signed-off-by: Kim B. Heino <Kim.Heino@bluegiga.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>