Add support for building android package

This commit adds the Android.mk to build for android.
Signed-off-by: Bin Li <bin.li@windriver.com>

android/Android.mk

+# Example: Android Native Library makefile for paho.mqtt.c
+# contributed by Bin Li <bin.li@windriver.com>
+
+LOCAL_PATH := $(call my-dir)
+libpaho-mqtt3_lib_path := ../src
+libpaho-mqtt3_c_includes := $(LOCAL_PATH)/$(libpaho-mqtt3_lib_path) \
+	external/hdc/android-ifaddrs \
+	external/openssl/include \
+	external/zlib
+
+# build sample util
+define build_sample_util
+__sample_module:= $1
+__sample_lib:= $2
+include $(CLEAR_VARS)
+LOCAL_C_INCLUDES := $(libpaho-mqtt3_c_includes)
+LOCAL_SHARED_LIBRARIES := $$(__sample_lib)
+LOCAL_MODULE := $$(__sample_module)
+LOCAL_SRC_FILES := $(libpaho-mqtt3_lib_path)/samples/$$(__sample_module).c
+include $(BUILD_EXECUTABLE)
+endef
+
+libpaho-mqtt3_local_src_c_files_common := \
+	$(libpaho-mqtt3_lib_path)/MQTTProtocolClient.c \
+	$(libpaho-mqtt3_lib_path)/Tree.c \
+	$(libpaho-mqtt3_lib_path)/Heap.c \
+	$(libpaho-mqtt3_lib_path)/MQTTPacket.c \
+	$(libpaho-mqtt3_lib_path)/Clients.c \
+	$(libpaho-mqtt3_lib_path)/Thread.c \
+	$(libpaho-mqtt3_lib_path)/utf-8.c \
+	$(libpaho-mqtt3_lib_path)/StackTrace.c \
+	$(libpaho-mqtt3_lib_path)/MQTTProtocolOut.c \
+	$(libpaho-mqtt3_lib_path)/Socket.c \
+	$(libpaho-mqtt3_lib_path)/Log.c \
+	$(libpaho-mqtt3_lib_path)/Messages.c \
+	$(libpaho-mqtt3_lib_path)/LinkedList.c \
+	$(libpaho-mqtt3_lib_path)/MQTTPersistence.c \
+	$(libpaho-mqtt3_lib_path)/MQTTPacketOut.c \
+	$(libpaho-mqtt3_lib_path)/SocketBuffer.c \
+	$(libpaho-mqtt3_lib_path)/MQTTPersistenceDefault.c \
+
+libpaho-mqtt3_local_src_c_files_c := \
+	$(libpaho-mqtt3_lib_path)/MQTTClient.c \
+
+libpaho-mqtt3_local_src_c_files_cs := \
+	$(libpaho-mqtt3_lib_path)/MQTTClient.c \
+	$(libpaho-mqtt3_lib_path)/SSLSocket.c \
+
+libpaho-mqtt3_local_src_c_files_a := \
+	$(libpaho-mqtt3_lib_path)/MQTTAsync.c \
+
+libpaho-mqtt3_local_src_c_files_as := \
+	$(libpaho-mqtt3_lib_path)/MQTTAsync.c \
+	$(libpaho-mqtt3_lib_path)/SSLSocket.c \
+
+# update the header file which normally generated by cmake
+$(shell (cp -f $(LOCAL_PATH)/$(libpaho-mqtt3_lib_path)/VersionInfo.h.in $(LOCAL_PATH)/$(libpaho-mqtt3_lib_path)/VersionInfo.h))
+$(shell (sed -i "s/@CLIENT_VERSION@/1.2.0/g" $(LOCAL_PATH)/$(libpaho-mqtt3_lib_path)/VersionInfo.h))
+$(shell ( sed -i "s/@BUILD_TIMESTAMP@/$(shell date)/g" $(LOCAL_PATH)/$(libpaho-mqtt3_lib_path)/VersionInfo.h))
+
+# building static libraries
+
+include $(CLEAR_VARS)
+LOCAL_MODULE    := libpaho-mqtt3c
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/$(libpaho-mqtt3_lib_path)
+LOCAL_C_INCLUDES:= $(libpaho-mqtt3_c_includes)
+LOCAL_SRC_FILES := $(libpaho-mqtt3_local_src_c_files_common) $(libpaho-mqtt3_local_src_c_files_c)
+include $(BUILD_STATIC_LIBRARY)
+
+include $(CLEAR_VARS)
+LOCAL_MODULE    := libpaho-mqtt3cs
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/$(libpaho-mqtt3_lib_path)
+LOCAL_C_INCLUDES:= $(libpaho-mqtt3_c_includes)
+LOCAL_CFLAGS += -DOPENSSL
+LOCAL_SRC_FILES := $(libpaho-mqtt3_local_src_c_files_common) $(libpaho-mqtt3_local_src_c_files_cs)
+include $(BUILD_STATIC_LIBRARY)
+
+include $(CLEAR_VARS)
+LOCAL_MODULE    := libpaho-mqtt3a
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/${libpaho-mqtt3_lib_path}
+LOCAL_C_INCLUDES:= $(libpaho-mqtt3_c_includes)
+LOCAL_SRC_FILES := $(libpaho-mqtt3_local_src_c_files_common) $(libpaho-mqtt3_local_src_c_files_a)
+include $(BUILD_STATIC_LIBRARY)
+  
+include $(CLEAR_VARS)
+LOCAL_MODULE    := libpaho-mqtt3as
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/${libpaho-mqtt3_lib_path}
+LOCAL_CFLAGS += -DOPENSSL
+LOCAL_C_INCLUDES:= $(libpaho-mqtt3_c_includes)
+LOCAL_SRC_FILES := $(libpaho-mqtt3_local_src_c_files_common) $(libpaho-mqtt3_local_src_c_files_as)
+include $(BUILD_STATIC_LIBRARY)
+
+# building shared libraries
+
+include $(CLEAR_VARS)
+LOCAL_MODULE    := libpaho-mqtt3c
+LOCAL_SHARED_LIBRARIES := libdl
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/$(libpaho-mqtt3_lib_path)
+LOCAL_C_INCLUDES:= $(libpaho-mqtt3_c_includes)
+LOCAL_SRC_FILES := $(libpaho-mqtt3_local_src_c_files_common) $(libpaho-mqtt3_local_src_c_files_c)
+include $(BUILD_SHARED_LIBRARY)
+
+include $(CLEAR_VARS)
+LOCAL_MODULE    := libpaho-mqtt3cs
+LOCAL_SHARED_LIBRARIES := libcrypto libssl libdl
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/$(libpaho-mqtt3_lib_path)
+LOCAL_C_INCLUDES:= $(libpaho-mqtt3_c_includes)
+LOCAL_CFLAGS += -DOPENSSL
+LOCAL_SRC_FILES := $(libpaho-mqtt3_local_src_c_files_common) $(libpaho-mqtt3_local_src_c_files_cs)
+include $(BUILD_SHARED_LIBRARY)
+
+include $(CLEAR_VARS)
+LOCAL_MODULE    := libpaho-mqtt3a
+LOCAL_SHARED_LIBRARIES := libdl
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/${libpaho-mqtt3_lib_path}
+LOCAL_C_INCLUDES:= $(libpaho-mqtt3_c_includes)
+LOCAL_SRC_FILES := $(libpaho-mqtt3_local_src_c_files_common) $(libpaho-mqtt3_local_src_c_files_a)
+include $(BUILD_SHARED_LIBRARY)
+ 
+include $(CLEAR_VARS)
+LOCAL_MODULE    := libpaho-mqtt3as
+LOCAL_SHARED_LIBRARIES := libcrypto libssl libdl
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/${libpaho-mqtt3_lib_path}
+LOCAL_CFLAGS += -DOPENSSL
+LOCAL_C_INCLUDES:= $(libpaho-mqtt3_c_includes)
+LOCAL_SRC_FILES := $(libpaho-mqtt3_local_src_c_files_common) $(libpaho-mqtt3_local_src_c_files_as)
+include $(BUILD_SHARED_LIBRARY)
+
+# building samples
+
+$(eval $(call build_sample_util, MQTTAsync_subscribe, libpaho-mqtt3a ) )
+$(eval $(call build_sample_util, MQTTAsync_publish, libpaho-mqtt3a ) )
+$(eval $(call build_sample_util, MQTTClient_publish, libpaho-mqtt3c ) )
+$(eval $(call build_sample_util, MQTTClient_publish_async, libpaho-mqtt3c ) )
+$(eval $(call build_sample_util, MQTTClient_subscribe, libpaho-mqtt3c ) )
+$(eval $(call build_sample_util, paho_c_pub, libpaho-mqtt3a ) )
+$(eval $(call build_sample_util, paho_c_sub, libpaho-mqtt3a ) )
+$(eval $(call build_sample_util, paho_cs_pub, libpaho-mqtt3c ) )
+$(eval $(call build_sample_util, paho_cs_sub, libpaho-mqtt3c ) )
+