runc only works on Linux so remove putative Solaris and unsupported main

Solaris runc equivalent is not open source. The unsupported option does
not build as other code is Linux specific.

Signed-off-by: Justin Cormack <justin.cormack@docker.com>

main_solaris.go

@@ -1,19 +0,0 @@
-package main
-
-import "github.com/urfave/cli"
-
-var (
-	checkpointCommand cli.Command
-	eventsCommand     cli.Command
-	restoreCommand    cli.Command
-	specCommand       cli.Command
-	killCommand       cli.Command
-	deleteCommand     cli.Command
-	execCommand       cli.Command
-	initCommand       cli.Command
-	listCommand       cli.Command
-	pauseCommand      cli.Command
-	resumeCommand     cli.Command
-	startCommand      cli.Command
-	stateCommand      cli.Command
-)

main_unsupported.go

@@ -1,13 +0,0 @@
-// +build !linux,!solaris
-
-package main
-
-import "github.com/urfave/cli"
-
-var (
-	checkpointCommand cli.Command
-	eventsCommand     cli.Command
-	restoreCommand    cli.Command
-	specCommand       cli.Command
-	killCommand       cli.Command
-)