Define RS_VERSION as the SDK version.

Change-Id: Iaee48b397923e7f6af33b6dfd4a03f52bdd34f93
diff --git a/Android.mk b/Android.mk
index 14604b9..7d1f240 100644
--- a/Android.mk
+++ b/Android.mk
@@ -24,6 +24,16 @@
 local_cflags_for_slang += -D__DISABLE_ASSERTS
 endif
 
+ifeq "REL" "$(PLATFORM_VERSION_CODENAME)"
+  RS_VERSION := $(PLATFORM_SDK_VERSION)
+else
+  # Increment by 1 whenever this is not a final release build, since we want to
+  # be able to see the RS version number change during development.
+  # See build/core/version_defaults.mk for more information about this.
+  RS_VERSION := "(1 + $(PLATFORM_SDK_VERSION))"
+endif
+local_cflags_for_slang += -DRS_VERSION=\"$(RS_VERSION)\"
+
 static_libraries_needed_by_slang := \
 	libLLVMLinker   \
 	libLLVMipo	\