scons: Remove the unused env.Label assignment in makeEnv.

Change-Id: I33fe01bb0381061528c450bc5e8312b52882615e
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/48128
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>

src/SConscript

@@ -1322,7 +1322,6 @@ def makeEnv(env, label, objsfx, **kwargs):
     libname = 'gem5_' + label
 
     new_env = env.Clone(OBJSUFFIX=objsfx, SHOBJSUFFIX=objsfx + 's')
-    new_env.Label = label
     new_env.Append(**kwargs)
 
     lib_sources = Source.all.with_tag(new_env, 'gem5 lib')