buildroot

libglib2: remove gdbus-codegen from target

It requires python and it's normally used at build time, hence since we
don't support toolchain in the target it really doesn't make much sense.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>