fix(SConstruct): Preserve PATH
fix(SConstruct): Preserve PATH

The new sysroot wrappers must be found via PATH since they don't replace
the GCC binaries in-place like the old bundled ones did.

mjg59/update_engine,endocode/update_engine,mjg59/update_engine,endocode/update_engine,mjg59/update_engine,endocode/update_engine