我正在尝试构建gem5，但出现以下错误。您能否指导是否需要设置一些环境变量？已安装所有必备组件。
$ uname -a
Linux i80pc93 4.4.0-148-generic #174~14.04.1-Ubuntu SMP Thu May 9 08:17:37 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
gem5$ scons build/ALPHA/gem5.opt
scons: Reading SConscript files ... Checking for C library python2.7... no Error: can't find library python2.7 required by python
gem5$ gcc --version
gcc (Ubuntu 4.8.5-4ubuntu8~14.04.2) 4.8.5 Copyright (C) 2015 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
gem5$ python --version
Python 2.7.6
我尝试重新安装不同版本的python和gcc，但是没有用。请指导。