Merge pull request #1593 from s7v7nislands/drop_go1.5

Drop support golang 1.5

libcontainer/compat_1.5_linux.go

@@ -1,10 +0,0 @@
-// +build linux,!go1.5
-
-package libcontainer
-
-import "syscall"
-
-// GidMappingsEnableSetgroups was added in Go 1.5, so do nothing when building
-// with earlier versions
-func enableSetgroups(sys *syscall.SysProcAttr) {
-}

libcontainer/setgroups_linux.go

@@ -1,11 +0,0 @@
-// +build linux,go1.5
-
-package libcontainer
-
-import "syscall"
-
-// Set the GidMappingsEnableSetgroups member to true, so the process's
-// setgroups proc entry wont be set to 'deny' if GidMappings are set
-func enableSetgroups(sys *syscall.SysProcAttr) {
-	sys.GidMappingsEnableSetgroups = true
-}