Use all-subdir-cpp-files instead of $(wildcard)

Bug: 24204119
Change-Id: I91cd75293a09a673a29b8d52e932ef85874fc239
diff --git a/Android.mk b/Android.mk
index defa384..cb5a73e 100644
--- a/Android.mk
+++ b/Android.mk
@@ -1,18 +1,13 @@
 LOCAL_PATH := $(call my-dir)
-ifeq ($(HOST_OS), linux)
 
 include $(CLEAR_VARS)
 LOCAL_MODULE := libxmlrpc++
+LOCAL_MODULE_HOST_OS := linux
 
 LOCAL_CLANG := true
 LOCAL_RTTI_FLAG := -frtti
 LOCAL_CPPFLAGS := -Wall -fexceptions
 LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/src
 
-xmlrpc_src_files := \
-    $(wildcard $(LOCAL_PATH)/src/*.cpp)
-LOCAL_SRC_FILES := \
-    $(xmlrpc_src_files:$(LOCAL_PATH)/%=%)
+LOCAL_SRC_FILES := $(call all-cpp-files-under,src)
 include $(BUILD_SHARED_LIBRARY)
-
-endif # HOST_OS == linux