[PATCH] tools: always create $STAGING_DIR/usr/{include,lib}

[Jo-Philipp Wich]

Hi,

> rules.mk always passes these as -I/-L to the toolchain.
> 
> Fixes rare errors like:
> cc1: error: staging_dir/target-aarch64_cortex-a53_musl/usr/include: No such file or directory [-Werror=missing-include-dirs]
> 
> Signed-off-by: Andre Heider <a.heider at gmail.com>

NAK - I'd prefer if we remove the faulty/redundant/unused include paths
from rules.mk instead.

~ Jo