libunarchive: stop using static data in archivers - archive_handle_t

libunarchive: stop using static data in archivers - archive_handle_t
 can trivially provide space for that.
rpm: code shrink
tar: simplify autodetection of bz2/.gz

function                                             old     new   delta
static.not_first                                       1       -      -1
static.end                                             1       -      -1
bb_makedev                                            51      49      -2
static.saved_hardlinks_created                         4       -      -4
static.saved_hardlinks                                 4       -      -4
longname                                               4       -      -4
linkname                                               4       -      -4
hash_file                                            251     247      -4
get_header_tar                                      1528    1521      -7
rpm_main                                            1711    1697     -14
get_header_cpio                                      965     944     -21
------------------------------------------------------------------------------
(add/remove: 0/6 grow/shrink: 0/5 up/down: 0/-66)             Total: -66 bytes
   text    data     bss     dec     hex filename
 804926     611    6868  812405   c6575 busybox_old
 804878     611    6852  812341   c6535 busybox_unstripped