hush: code shrink

hush: code shrink

function                                             old     new   delta
run_pipe                                            1589    1591      +2
pseudo_exec_argv                                     374     375      +1
builtin_type                                         114     115      +1
find_function                                          8       -      -8
------------------------------------------------------------------------------
(add/remove: 0/1 grow/shrink: 3/0 up/down: 4/-8)               Total: -4 bytes

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