stage1 修复设计问题 实现ir2vm

stage0/spl_mcode.h

@@ -201,6 +201,7 @@ void spl_prog_drop(spl_prog_t *prog);
 int spl_prog_load_from_file(const char *fname, spl_prog_t *prog);
 int spl_prog_store_to_file(const char *fname, spl_prog_t *prog);
 
+int spl_prog_add_instr(spl_prog_t *prog, uint8_t opcode, uint8_t type, spl_val_t imm);
 int spl_prog_add_data(spl_prog_t *prog, void *ptr, usize size);
 int spl_prog_add_func(spl_prog_t *prog, spl_func_t *func);
 int spl_prog_add_native(spl_prog_t *prog, spl_native_t *native);