Missing getter and additional tests.

Change-Id: I057dd0a29d2cad40d0a0627b4355faeb82bbc229
diff --git a/scriptc/rs_allocation.rsh b/scriptc/rs_allocation.rsh
index e890021..661d3e3 100644
--- a/scriptc/rs_allocation.rsh
+++ b/scriptc/rs_allocation.rsh
@@ -290,5 +290,13 @@
 extern rs_data_kind __attribute__((overloadable))
     rsElementGetDataKind(rs_element e);
 
+/**
+ * @param e element to get data from
+ * @return length of the element vector (for float2, float3,
+ *         etc.)
+ */
+extern uint32_t __attribute__((overloadable))
+    rsElementGetVectorSize(rs_element e);
+
 #endif