Use a (somewhat) more documented environment variable.

I believe OUT is not mandatory to define, whereas
ANDROID_PRODUCT_OUT is. Not sure our continuous tests define it.

Change-Id: I7cd23971384df265e59587b49760aba29133a59c
diff --git a/test/run-test b/test/run-test
index 1ed03ea..0e42efe 100755
--- a/test/run-test
+++ b/test/run-test
@@ -194,10 +194,10 @@
 fi
 
 # Most interesting target architecture variables are Makefile variables, not environment variables.
-# Try to map the suffix64 flag and what we find in ${OUT}/data/art-test to an architecture name.
+# Try to map the suffix64 flag and what we find in ${ANDROID_PRODUCT_OUT}/data/art-test to an architecture name.
 function guess_arch_name() {
-    grep32bit=`ls ${OUT}/data/art-test | grep -E '^(arm|x86|mips)$'`
-    grep64bit=`ls ${OUT}/data/art-test | grep -E '^(arm64|x86_64)$'`
+    grep32bit=`ls ${ANDROID_PRODUCT_OUT}/data/art-test | grep -E '^(arm|x86|mips)$'`
+    grep64bit=`ls ${ANDROID_PRODUCT_OUT}/data/art-test | grep -E '^(arm64|x86_64)$'`
     if [ "x${suffix64}" = "x64" ]; then
         target_arch_name=${grep64bit}
     else
@@ -230,7 +230,7 @@
 
 if [ "$runtime" = "dalvik" ]; then
     if [ "$target_mode" = "no" ]; then
-        framework="${OUT}/system/framework"
+        framework="${ANDROID_PRODUCT_OUT}/system/framework"
         bpath="${framework}/core.jar:${framework}/conscrypt.jar:${framework}/okhttp.jar:${framework}/core-junit.jar:${framework}/bouncycastle.jar:${framework}/ext.jar"
         run_args="${run_args} --boot -Xbootclasspath:${bpath}"
     else