libcore tests: increase the timeout in debug mode.

libcore.java.lang.SystemTest#testArrayCopyConcurrentModification
is slow on device.

Change-Id: I21e6533b2a3199e9e85d17b059065a6289553f8b
diff --git a/tools/run-libcore-tests.sh b/tools/run-libcore-tests.sh
index 1b8748b..e28de09 100755
--- a/tools/run-libcore-tests.sh
+++ b/tools/run-libcore-tests.sh
@@ -84,7 +84,7 @@
     # Increase the timeout, as vogar cannot set individual test
     # timeout when being asked to run packages, and some tests go above
     # the default timeout.
-    vogar_args="$vogar_args --timeout 180"
+    vogar_args="$vogar_args --timeout 240"
     shift
   elif [[ "$1" == "" ]]; then
     break