slang: Add the name of the metadata node for reduce kernels.

Bug: 22631253

Synced with libbcc/bcinfo/MetadataExtractor.cpp

Change-Id: I46d1ef5206aa0afa6226b1a703ec30aa8069ee9a
diff --git a/slang_rs_metadata.h b/slang_rs_metadata.h
index 63e7e0f..b84a8cd 100644
--- a/slang_rs_metadata.h
+++ b/slang_rs_metadata.h
@@ -33,4 +33,6 @@
 
 #define RS_EXPORT_FOREACH_MN "#rs_export_foreach"
 
+#define RS_EXPORT_REDUCE_MN "#rs_export_reduce"
+
 #endif  // _FRAMEWORKS_COMPILE_SLANG_SLANG_RS_METADATA_H_  NOLINT