scons: Extract the gem5 specific Configure call to its own file.

This modularizes that fairly generic code and pulls it out of the main
SConstruct file.

Change-Id: I5f5edc866af43753b4e0a9cc63774ded0fffe06b
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/40858
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
3 files changed