dev-util/scons: 3.0.5-r1 fix passthrough of $PATH env

dev-util/scons: 3.0.5-r1 fix passthrough of $PATH env

The env-passthrough patch make possible to pass $PATH env
to scons build env while build of packages that use scons
as build system by call of escons() function from scons-util.eclass.
The escons() func. setup GENTOO_SCONS_ENV_PASSTHROUGH=1 variable
that make the patch mentioned above to be working.

The scons package doesn't call escons() so it get to setup
GENTOO_ENV_PASSTHROUTH=1 variable directly within python_test() phase.

This fix repairs Clang tests that failed because the clang and clang++
couldn't be found within scons test env.

Signed-off-by: Sergey Torokhov <torokhov_s_a@mail.ru>
Signed-off-by: Michał Górny <mgorny@gentoo.org>