Add the StringPiece class.

Change-Id: I4e8c303261f79553cfe4853d5c7e1adf851496fc
diff --git a/Android.common.mk b/Android.common.mk
index e21ba10..3dce0b5 100644
--- a/Android.common.mk
+++ b/Android.common.mk
@@ -46,7 +46,8 @@
 	src/memory_region.cc \
 	src/object.cc \
 	src/raw_dex_file.cc \
-	src/runtime.cc
+	src/runtime.cc \
+	src/stringpiece.cc
 
 ifeq ($(LIBART_TARGET_ARCH),arm)
 LIBART_LOCAL_SRC_FILES += \