external/ci: add linux 32 bit builds

[Thinkofname]

Pretty sure there is a reason why the builds are currently disabled. Need to look into it

Reason:

$ go install -v github.com/thinkofdeath/steven/cmd/steven
github.com/go-gl/glfw/v3.1/glfw
# github.com/go-gl/glfw/v3.1/glfw
/usr/bin/ld: cannot find -lGL
/usr/bin/ld: cannot find -lX11
/usr/bin/ld: cannot find -lXrandr
/usr/bin/ld: cannot find -lXxf86vm
/usr/bin/ld: cannot find -lXi
/usr/bin/ld: cannot find -lXcursor
/usr/bin/ld: cannot find -lXinerama
collect2: error: ld returned 1 exit status
github.com/thinkofdeath/gl/v3.2-core/gl
# github.com/thinkofdeath/gl/v3.2-core/gl
/usr/bin/ld: cannot find -lGL
/usr/bin/ld: cannot find -lGL
collect2: error: ld returned 1 exit status