busybox

vi: move mark[i] pointers if text[] moves after realloc

While at it, optimized :s/find/repl/ a bit

function                                             old     new   delta
text_hole_make                                       120     150     +30
colon                                               2848    2844      -4

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