pkg/specgen: remove config_unsupported.go

This is not used at all but causes a libimage import for non linux
builds which causes bloat for them, with the new !remote tag this is no
longer possible and we have to remove it to fix the build.

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

pkg/specgen/config_unsupported.go

@@ -1,15 +0,0 @@
-//go:build !linux
-// +build !linux
-
-package specgen
-
-import (
-	"errors"
-
-	"github.com/containers/common/libimage"
-	spec "github.com/opencontainers/runtime-spec/specs-go"
-)
-
-func (s *SpecGenerator) getSeccompConfig(configSpec *spec.Spec, img *libimage.Image) (*spec.LinuxSeccomp, error) {
-	return nil, errors.New("function not supported on non-linux OS's")
-}