Refine aot stack overflow check and enhance wasm loader malformed checks (#248)

And separate global data from wasm memory instance

core/iwasm/compilation/aot.h

@@ -98,6 +98,8 @@ typedef struct AOTFunc {
   uint32 func_type_index;
   uint32 local_count;
   uint8 *local_types;
+  uint16 param_cell_num;
+  uint16 local_cell_num;
   uint32 code_size;
   uint8 *code;
 } AOTFunc;