libbb: invert the meaning of SETUP_ENV_NO_CHDIR -> SETUP_ENV_CHDIR

Double negatives are hard to grok.

function                                             old     new   delta
login_main                                           986     988      +2
su_main                                              474     470      -4
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/1 up/down: 2/-4)               Total: -2 bytes

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