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()

wamr-compiler/CMakeLists.txt

@@ -121,7 +121,7 @@ add_library (vmlib
 
 add_library (aotclib ${IWASM_COMPL_SOURCE})
 
-add_executable (wamrc main.c ext_lib_export.c)
+add_executable (wamrc main.c)
 
 target_link_libraries (wamrc aotclib vmlib ${LLVM_AVAILABLE_LIBS} -lm -ldl -lpthread)
 

wamr-compiler/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"