Add new E_TYPE_XIP to indicate XIP mode (#874)

Emit e_type = E_TYPE_XIP in target info section to indicate that it is
an XIP file, and replace related checks in aot loader.

core/iwasm/aot/aot_runtime.h

@@ -135,7 +135,6 @@ typedef struct AOTModule {
     AOTMemInitData **mem_init_data_list;
 
     /* native symbol */
-    uint32 native_symbol_count;
     void **native_symbol_list;
 
     /* import tables */
@@ -246,6 +245,9 @@ typedef struct AOTModule {
     /* is jit mode or not */
     bool is_jit_mode;
 
+    /* is indirect mode or not */
+    bool is_indirect_mode;
+
 #if WASM_ENABLE_JIT != 0
     WASMModule *wasm_module;
     AOTCompContext *comp_ctx;