Implement native function pointer check, addr conversion and register, update documents (#185)

Modified WASM runtime API:
- wasm_runtime_module_malloc()
- wasm_runtime_lookup_function()
Introduced runtime API
- wasm_runtime_register_natives()

product-mini/platforms/darwin/CMakeLists.txt

@@ -62,7 +62,7 @@ set (WAMR_ROOT_DIR ${CMAKE_CURRENT_SOURCE_DIR}/../../..)
 include (${WAMR_ROOT_DIR}/build-scripts/runtime_lib.cmake)
 add_library(vmlib ${WAMR_RUNTIME_LIB_SOURCE})
 
-add_executable (iwasm main.c ext_lib_export.c)
+add_executable (iwasm main.c)
 
 install (TARGETS iwasm DESTINATION bin)
 

product-mini/platforms/darwin/ext_lib_export.c

@@ -1,10 +0,0 @@
-/*
- * Copyright (C) 2019 Intel Corporation.  All rights reserved.
- * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
- */
-
-#include "lib_export.h"
-
-static NativeSymbol extended_native_symbol_defs[] = { };
-
-#include "ext_lib_export.h"