Fix some compiler warnings emitted by gcc-4.8.0

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
wget: if FEATURE_CLEAN_UP, free(ptr_to_globals)

Signed-off-by: Guilherme Maciel Ferreira <guilherme.maciel.ferreira@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
tail compat: fix header printing for tail -f

Makes tail -f for multiple files display the header only if another (ie. not
currently displayed) file changed.

Signed-off-by: Bartosz Golaszewski <bartekgola@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
bloat-o-meter: add usage info

Signed-off-by: Bartosz Golaszewski <bartekgola@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
libbb: use <poll.h> instead of <sys/poll.h>

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>