busybox

hush: fix exec builtin in a better way (+ "glob in exec" bug fixed)

function                                             old     new   delta
execvp_or_die                                          -      50     +50
static.pseudo_null_str                                 3       -      -3
builtin_exec                                          83      57     -26
pseudo_exec_argv                                     200     163     -37
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(add/remove: 1/1 grow/shrink: 0/2 up/down: 50/-66)            Total: -16 bytes

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