How do I find out whether the 'mgetty' binary installed from its rpm is compiled with -DAUTO_PPP or not? Or going further and generalizing, how do I find the flags that were used to compile a binary?

I have configured my machine as a dialin server. Currently, mgetty accepts the username and then calls /bin/login to accept and authenticate the password from the peer. But I want pppd to authenticate the peer rather than /bin/login. So mgetty should call pppd rather than /bin/login. The file /etc/mgetty+sendfax/login.config has the option for doing this. But a comment in the file says that mgetty has to be compiled with -DAUTO_PPP option for it to work. I suspect that the currently installed mgetty binary isn't compiled with -DAUTO_PPP because even after enabling /AutoPPP/ in login.config, the remote client still gets a bash prompt after authenticating which indicates /bin/login being called.

I read the installed mgetty documentation but it doesn't say anything about the AutoPPP option being used while compiling or not.