Running make here will create a standalone version of FS-UAE which (only)
depends on the Steam runtime. You need to run make from within a Steam
runtime shell (i.e. shell-i386.sh or shell-amd64.sh) from the Steam
runtime SDK.

The result, if successful, will be an fs-uae-[version]-steamos-[arch].tar.xz
file placed in the parent directory 

Please note, while this directory, and the resulting tarball contain the
name "steamos", the dependency is really on the Steam runtime and not SteamOS.
So the binaries should work on all systems where the Linux Steam runtime
works.
