Revert "Remove DIST_DIR uses in ART."

This reverts commit 89e5a9f0e3dbb33d9dd6be6cffbc74e93a6c8faa.

Reason for revert: fixed with https://android-review.googlesource.com/c/platform/build/soong/+/796459

Test: art/test/testrunner/testrunner.py --host -b -t 001-HelloWorld
Change-Id: Icde2015f110f135f2010d603d764a51aa5ae07a5
diff --git a/test/testrunner/env.py b/test/testrunner/env.py
index 600edfa..1f4b829 100644
--- a/test/testrunner/env.py
+++ b/test/testrunner/env.py
@@ -141,4 +141,5 @@
 # include platform prebuilt java, javac, etc in $PATH.
 os.environ['PATH'] = ANDROID_JAVA_TOOLCHAIN + ':' + os.environ['PATH']
 
+DIST_DIR = _get_build_var('DIST_DIR')
 SOONG_OUT_DIR = _get_build_var('SOONG_OUT_DIR')
diff --git a/tools/build/var_list b/tools/build/var_list
index 1ffbe6b..98a5472 100644
--- a/tools/build/var_list
+++ b/tools/build/var_list
@@ -35,4 +35,5 @@
 ANDROID_JAVA_TOOLCHAIN
 
 # b/62653020
+DIST_DIR
 SOONG_OUT_DIR