python3: remove two setup.py cross-compile hacks

python3: remove two setup.py cross-compile hacks

Remove two unneeded hacks. The first hack ("setup.py: no host headers
libs" patch) is not needed because we use cross-compiler (e.g.
i586-oe-linux-gcc) which has not been configured with any host system
include or library directories, and thus, we don't get any host system
directories when running "gcc -E -v".

The second hack becomes useless after the first hack has been removed
and we get the standard include and lib directories normally from gcc.

Signed-off-by: Markus Lehtonen <markus.lehtonen@linux.intel.com>