Fix RenderScript JNI code build issue.

We should not try to build the JNI file until after we have built the
the generated header files that it includes.
diff --git a/Android.mk b/Android.mk
index 83d3d66..108836f 100644
--- a/Android.mk
+++ b/Android.mk
@@ -54,6 +54,8 @@
 $(GEN) : $(RSG_GENERATOR) $(LOCAL_PATH)/rs.spec
 $(GEN): $(intermediates)/%.h : $(LOCAL_PATH)/%.h.rsg
 	$(transform-generated-source)
+
+RS_GENERATED_SOURCES += $(GEN)
 LOCAL_GENERATED_SOURCES += $(GEN)
 
 # Generate custom source files
@@ -62,11 +64,13 @@
             rsgApi.cpp \
             rsgApiReplay.cpp \
         )
-        
+
 $(GEN) : PRIVATE_CUSTOM_TOOL = $(RSG_GENERATOR) $< $@ <$(TOP_LOCAL_PATH)/rs.spec
 $(GEN) : $(RSG_GENERATOR) $(LOCAL_PATH)/rs.spec
 $(GEN): $(intermediates)/%.cpp : $(LOCAL_PATH)/%.cpp.rsg
 	$(transform-generated-source)
+
+RS_GENERATED_SOURCES += $(GEN)
 LOCAL_GENERATED_SOURCES += $(GEN)
 
 LOCAL_SRC_FILES:= \
@@ -127,6 +131,8 @@
 
 LOCAL_MODULE:= libRS_jni
 
+LOCAL_ADDITIONAL_DEPENDENCIES += $(RS_GENERATED_SOURCES)
+
 include $(BUILD_SHARED_LIBRARY)
 
 include $(call all-subdir-makefiles)