lzop: reuse strings

lzop: reuse strings

function                                             old     new   delta
lzo_compress                                         470     483     +13
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/0 up/down: 13/0)               Total: 13 bytes
   text    data     bss     dec     hex filename
 940011     477    7284  947772   e763c busybox_old
 939976     477    7284  947737   e7619 busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>