scons: Fix variable not found error

Change-Id: I09708fea777a57a35e55409c8997ed0b25de2b46
Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/64012
Tested-by: kokoro <noreply+kokoro@google.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Melissa Jost <melissakjost@gmail.com>
diff --git a/site_scons/gem5_scons/__init__.py b/site_scons/gem5_scons/__init__.py
index c958e22..7214876 100644
--- a/site_scons/gem5_scons/__init__.py
+++ b/site_scons/gem5_scons/__init__.py
@@ -264,7 +264,7 @@
     while path_dirs and path_dirs[-1] != "build":
         variant_dir = path_dirs.pop()
     if not path_dirs:
-        error("No non-leaf 'build' dir found on target path.", t)
+        error("No non-leaf 'build' dir found on target path.", target)
 
     return os.path.join("/", *path_dirs), variant_dir