ART: Allow multiple invoke-with for art script

Just like run-test, allow multiple invoke-with arguments that are
chained together.

Change-Id: I9f0d2d23fbff1cef32f0bb69e1bb803e157cfb73
diff --git a/tools/art b/tools/art
index 2408f9f..6c89a60 100644
--- a/tools/art
+++ b/tools/art
@@ -45,7 +45,7 @@
 while true; do
   if [ "$1" = "--invoke-with" ]; then
     shift
-    invoke_with="$1"
+    invoke_with="$invoke_with $1"
     shift
   elif [ "$1" = "-d" ]; then
     LIBART="libartd.so"