Clean up Android.mk.

- Move away from the deprecated LOCAL_COPY_HEADERS to
  LOCAL_EXPORT_C_INCLUDE_DIRS.
- Remove unnecessary additional dependencies on Android.mk since
  the build system now does this by default.
- Remove unnecessary hardcoded include paths for dependencies that
  set LOCAL_EXPORT_C_INCLUDE_DIRS.

Change-Id: I8a4d2ff9c3c4893499f246d2a4147413fdd4db50
diff --git a/Android.mk b/Android.mk
index 9444620..d99ad90 100644
--- a/Android.mk
+++ b/Android.mk
@@ -47,27 +47,15 @@
 	endif
 endif
 
-common_C_INCLUDES +=
-
-common_COPY_HEADERS_TO := libpng
-common_COPY_HEADERS := png.h pngconf.h pngusr.h
-
 # For the host
 # =====================================================
 
 include $(CLEAR_VARS)
-LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/Android.mk
-
 LOCAL_SRC_FILES := $(common_SRC_FILES)
 LOCAL_CFLAGS += $(common_CFLAGS)
 LOCAL_ASFLAGS += $(common_ASFLAGS)
-LOCAL_C_INCLUDES += $(common_C_INCLUDES) external/zlib
-
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)
 LOCAL_MODULE:= libpng
-
-LOCAL_COPY_HEADERS_TO := $(common_COPY_HEADERS_TO)
-LOCAL_COPY_HEADERS := $(common_COPY_HEADERS)
-
 include $(BUILD_HOST_STATIC_LIBRARY)
 
 
@@ -75,7 +63,6 @@
 # =====================================================
 
 include $(CLEAR_VARS)
-LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/Android.mk
 LOCAL_CLANG := true
 LOCAL_SRC_FILES := $(common_SRC_FILES)
 LOCAL_CFLAGS += $(common_CFLAGS) -ftrapv
@@ -85,21 +72,15 @@
 LOCAL_CFLAGS_arm64 := $(my_cflags_arm64)
 LOCAL_SRC_FILES_arm64 := $(my_src_files_arm)
 LOCAL_ADDRESS_SANITIZER := false
-
-LOCAL_C_INCLUDES += $(common_C_INCLUDES) \
-	external/zlib
-LOCAL_SHARED_LIBRARIES := \
-	libz
-
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)
+LOCAL_SHARED_LIBRARIES := libz
 LOCAL_MODULE:= libpng
-
 include $(BUILD_STATIC_LIBRARY)
 
 # For the device (shared)
 # =====================================================
 
 include $(CLEAR_VARS)
-LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/Android.mk
 LOCAL_CLANG := true
 LOCAL_SRC_FILES := $(common_SRC_FILES)
 LOCAL_CFLAGS += $(common_CFLAGS) -ftrapv
@@ -108,26 +89,16 @@
 LOCAL_SRC_FILES_arm := $(my_src_files_arm)
 LOCAL_CFLAGS_arm64 := $(my_cflags_arm64)
 LOCAL_SRC_FILES_arm64 := $(my_src_files_arm)
-
-LOCAL_C_INCLUDES += $(common_C_INCLUDES) \
-	external/zlib
-LOCAL_SHARED_LIBRARIES := \
-	libz
-
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)
+LOCAL_SHARED_LIBRARIES := libz
 LOCAL_MODULE:= libpng
-
-LOCAL_COPY_HEADERS_TO := $(common_COPY_HEADERS_TO)
-LOCAL_COPY_HEADERS := $(common_COPY_HEADERS)
-
 include $(BUILD_SHARED_LIBRARY)
 
 # For testing
 # =====================================================
 
 include $(CLEAR_VARS)
-LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/Android.mk
 LOCAL_CLANG := true
-LOCAL_C_INCLUDES:= $(common_C_INCLUDES) external/zlib
 LOCAL_SRC_FILES:= pngtest.c
 LOCAL_MODULE := pngtest
 LOCAL_SHARED_LIBRARIES:= libpng libz