stage2 提供c后端 提交stage1的测试

stage0/spl_mcode.h

@@ -195,6 +195,7 @@ void spl_prog_dump(spl_prog_t *prog);
 
 
 int spl_prog_load_from_file(const char *fname, spl_prog_t *prog);
+int spl_prog_load_from_buffer(const char *buffer, usize len, 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_vm_val_t imm);