Switch to libsigchain.a

Use LOCAL_WHOLE_STATIC_LIBRARIES to instruct static linker
  to export symbols from the static library.

(cherry picked from commit 4340a14fbf)

Bug: 18701723
Change-Id: I70f6fdb64b0d1adbadf96c8de85870a903ec186a

services/surfaceflinger/Android.mk

@@ -115,15 +115,11 @@ include $(BUILD_SHARED_LIBRARY)
 include $(CLEAR_VARS)
 
 LOCAL_LDFLAGS := -Wl,--version-script,art/sigchainlib/version-script.txt -Wl,--export-dynamic
-LOCAL_CFLAGS:= -DLOG_TAG=\"SurfaceFlinger\" -Iart
+LOCAL_CFLAGS:= -DLOG_TAG=\"SurfaceFlinger\"
 LOCAL_CPPFLAGS:= -std=c++11
 
-# TODO: Trying to link libsigchain as a static library prevents
-# static linker from exporting necessary symbols. So as a workaround
-# we use sigchain.o
 LOCAL_SRC_FILES:= \
-	main_surfaceflinger.cpp \
-	sigchain_proxy.cpp
+	main_surfaceflinger.cpp
 
 LOCAL_SHARED_LIBRARIES := \
 	libsurfaceflinger \
@@ -133,6 +129,8 @@ LOCAL_SHARED_LIBRARIES := \
 	libutils \
 	libdl
 
+LOCAL_WHOLE_STATIC_LIBRARIES := libsigchain
+
 LOCAL_MODULE:= surfaceflinger
 
 ifdef TARGET_32_BIT_SURFACEFLINGER

services/surfaceflinger/sigchain_proxy.cpp

@@ -1,17 +0,0 @@
-/*
- * Copyright (C) 2014 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "sigchainlib/sigchain.cc"