Refine call native function from AOT code (#1015)

When calling native function from AOT code, current implementation is to return
back to runtime to call aot_invoke_native, which calls wasm_runtime_invoke_native
and the latter calls assembly code. We did it before as there may be pointer and
string arguments to check and convert if the native function's registered signature
has character '*' and '$'.
As the built-in native function's signatures can be gotten in compilation time, we
check the pointer/string arguments and convert them into native address in AOT
code, and then invoke the native function directly, so as to improve performance.

core/iwasm/aot/aot_runtime.h

@@ -647,6 +647,11 @@ bool
 aot_call_indirect(WASMExecEnv *exec_env, uint32 tbl_idx, uint32 table_elem_idx,
                   uint32 argc, uint32 *argv);
 
+bool
+aot_check_app_addr_and_convert(AOTModuleInstance *module_inst, bool is_str,
+                               uint32 app_buf_addr, uint32 app_buf_size,
+                               void **p_native_addr);
+
 uint32
 aot_get_plt_table_size();