Add clean step after recent changes

out/target/common/obj/APPS/Gallery2_intermediates/src/renderscript
/src/com/android/gallery3d/filtershow/filters/ScriptC_convolve3x3.java:24:
error: package android.support.v8.renderscript does not exist

Change-Id: I8411ec214607d0875bea5e41d93b416585e15592