Android Linux Doom

I have been contemplating on porting Linux Doom to Android.

The first thing I'm starting off with is the SNDSERV but having a bit of a compiling problem it's just one thing that I'm having trouble with it is it's saying

"NDK: jni/linux.c:66: error: undefined reference to 'errno'

"NDK: collect2: error: ld returned 1 exit status"

Heres the code:

Android Linux Doom snd serv

Out of curiosity, why Linux Doom?

To give it a more  nostalgic feel to it with no enhancements like with all of the other source ports like PrBoom, GZDoom, Zandronum. Plus I'm sure no one thought of porting linux doom to android.