hush: fix two nasty bugs:

hush: fix two nasty bugs:
hush-bugs/tick2.tests: ok
hush-bugs/tick.tests: ok

function                                             old     new   delta
parse_stream                                        1332    1557    +225
b_addptr                                               -      97     +97
add_till_backquote                                     -      82     +82
b_addstr                                               -      58     +58
b_grow_by                                              -      50     +50
setup_string_in_str                                    -      29     +29
expand_variables                                    1196    1199      +3
expand_on_ifs                                        100      97      -3
b_addqchr                                             57      50      -7
parse_and_run_string                                  48      31     -17
lookup_param                                          27       -     -27
b_addchr                                              75      45     -30
count_ifs                                             44       -     -44
process_command_subs                                 222       -    -222
------------------------------------------------------------------------------
(add/remove: 5/3 grow/shrink: 2/4 up/down: 544/-350)          Total: 194 bytes
   text    data     bss     dec     hex filename
 759354     604    6684  766642   bb2b2 busybox_old
 759534     604    6684  766822   bb366 busybox_unstripped