scons: Declare PySource Source files in the PySource __init__.

There's no reason to wait until the end to loop over all PySource files
and declare their Source-s then.

Change-Id: I94de1b2123bb94324a647bbc005a923012080cab
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/49386
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Hoa Nguyen <hoanguyen@ucdavis.edu>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
1 file changed