busybox

ash,hush: fix ulimit to be more bash-compat, closes 11791

function                                             old     new   delta
shell_builtin_ulimit                                 486     651    +165
limit_chars                                            -      14     +14
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(add/remove: 1/0 grow/shrink: 1/0 up/down: 179/0)             Total: 179 bytes

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