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/962-iface-static/build b/test/962-iface-static/build
index 5ad82f7..06bb3bd 100755
--- a/test/962-iface-static/build
+++ b/test/962-iface-static/build
@@ -26,5 +26,5 @@
 fi
 
 # Build the smali files and make a dex
-${SMALI} -JXmx512m --experimental --api-level 23 --output classes.dex $(find smali -name '*.smali')
+${SMALI} -JXmx512m ${SMALI_ARGS} --output classes.dex $(find smali -name '*.smali')
 zip $TEST_NAME.jar classes.dex