less: improve search when data is not supplied fast enough by stdin -

less: improve search when data is not supplied fast enough by stdin -
now will try reading for 1-2 seconds before declaring that there is no match.
This fixes a very common annoyance with long manpages.

function                                             old     new   delta
read_lines                                           653     719     +66
buffer_down                                           28      83     +55
goto_match                                           140     141      +1
cap_cur_fline                                         72       -     -72
------------------------------------------------------------------------------
(add/remove: 0/1 grow/shrink: 3/0 up/down: 122/-72)            Total: 50 bytes
   text    data     bss     dec     hex filename
 798734     661    7428  806823   c4fa7 busybox_old
 798768     661    7428  806857   c4fc9 busybox_unstripped