Cleanup some of the run-test system

Make run-test cleaner when using experimental default methods and
lambdas. Adds a --experimental <type> flag that adds the required
experimental compiler and runtime flags.

Change-Id: Ia9327b44e14597a400bf279fc946a43619f1355c
diff --git a/test/etc/default-build b/test/etc/default-build
index c92402b..4743216 100755
--- a/test/etc/default-build
+++ b/test/etc/default-build
@@ -96,7 +96,7 @@
 
 if [ -d smali ]; then
   # Compile Smali classes
-  ${SMALI} -JXmx256m --experimental --api-level 23 --output smali_classes.dex `find smali -name '*.smali'`
+  ${SMALI} -JXmx256m ${SMALI_ARGS} --output smali_classes.dex `find smali -name '*.smali'`
 
   # Don't bother with dexmerger if we provide our own main function in a smali file.
   if [ ${SKIP_DX_MERGER} = "false" ]; then