Fix UC_HOOK_EDGE_GENERATED to work with indirect jump

For an indirect jump (lookup_tb_ptr), last_tb would be NULL

include/uc_priv.h

@@ -357,6 +357,8 @@ struct uc_struct {
 
     sigjmp_buf jmp_bufs[UC_MAX_NESTED_LEVEL]; // To support nested uc_emu_start
     int nested_level;                         // Current nested_level
+
+    struct TranslationBlock* last_tb; // The real last tb we executed.
 };
 
 // Metadata stub for the variable-size cpu context used with uc_context_*()