tools: suggest python2 command in configure

Try and find a suitable python2 binary and suggest it to the user in
case they start the configure script with a incompatible version.

PR-URL: https://github.com/nodejs/node/pull/11375


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>