vi: fix the bug where vi never grows the edit buffer.

vi: fix the bug where vi never grows the edit buffer.
vi: do G trick on it

function                                             old     new   delta
place_cursor                                         264     276     +12
next_tabstop                                          22      34     +12
mycmp                                                 44      52      +8
status_line                                           34      40      +6
yank_delete                                           89      92      +3
what_reg                                              34      37      +3
suspend_sig                                           63      66      +3
find_range                                           493     496      +3
redraw                                               104     106      +2
cont_sig                                              63      65      +2
Indicate_Error                                        59      61      +2
status_line_bold                                      71      72      +1
file_insert                                          327     328      +1
vi_setops                                              1       -      -1
...
cmdcnt                                                 4       -      -4
chars_to_parse                                         4       -      -4
ccol                                                   4       -      -4
dot_scroll                                            88      79      -9
stupid_insert                                         28      18     -10
winch_sig                                            102      91     -11
char_insert                                          353     336     -17
readit                                               354     336     -18
get_one_char                                         128     110     -18
init_text_buffer                                     171     152     -19
text_hole_delete                                     132     112     -20
edit_file                                            940     918     -22
get_input_line                                       198     168     -30
show_status_line                                     449     408     -41
colon                                               3112    3067     -45
vi_main                                              312     250     -62
refresh                                             1077     974    -103
do_cmd                                              4818    4483    -335
------------------------------------------------------------------------------
(add/remove: 0/38 grow/shrink: 13/20 up/down: 58/-889)       Total: -831 bytes
   text    data     bss     dec     hex filename
 809566     612    7044  817222   c7846 busybox_old
 808794     611    6924  816329   c74c9 busybox_unstripped

   text    data     bss     dec     hex filename
  18888       1     122   19011    4a43 busybox.t8/editors/vi.o
  18116       0       0   18116    46c4 busybox.t9/editors/vi.o