rs: Fix RS_VERSION define

Commit 51dc7a27a8749d4ad43169bf39d4378529e132cd broke the RS_VERSION
define by setting LOCAL_CFLAGS := something after the addition of
LOCAL_CFLAGS += -DRS_VERSION=...

Make sure the := definition occurs before the += amendment.

Change-Id: I320ae9215f3ef2982c707a6ecaf5a14880ffa036
Signed-off-by: Bernhard Rosenkraenzer <Bernhard.Rosenkranzer@linaro.org>
diff --git a/cpp/Android.mk b/cpp/Android.mk
index a03a5de..de3e615 100644
--- a/cpp/Android.mk
+++ b/cpp/Android.mk
@@ -11,6 +11,7 @@
 endif
 local_cflags_for_rs_cpp += -DRS_VERSION=$(RS_VERSION)
 
+LOCAL_CFLAGS := $(call-cc-cpp-option,-Qunused-arguments)
 LOCAL_CFLAGS += $(local_cflags_for_rs_cpp)
 
 LOCAL_SRC_FILES:= \
@@ -34,8 +35,6 @@
 
 LOCAL_MODULE_TAGS := optional
 
-LOCAL_CFLAGS := $(call-cc-cpp-option,-Qunused-arguments)
-
 intermediates := $(call intermediates-dir-for,STATIC_LIBRARIES,libRS,TARGET,)
 librs_generated_headers := \
     $(intermediates)/rsgApiStructs.h \