libbb: introduce and use chdir_or_warn()

function                                             old     new   delta
chdir_or_warn                                          -      37     +37
send_cgi_and_exit                                    720     711      -9
xchdir                                                27      15     -12
setup_environment                                    233     217     -16
fork_job                                             449     433     -16
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(add/remove: 1/0 grow/shrink: 0/4 up/down: 37/-53)            Total: -16 bytes

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