lsof: do not remove WIDECHARINCL definition

WIDECHARINCL is enabled by HASWIDECHAR, so removing its definition if
BR2_USE_WCHAR is not set is useless.

Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>