If newuidmap or newgidmap fail, then check their permissions

Often distributions to not have newuidmap and netgidmap configured
to be setuid. If Podman fails to setup the user namespace, check to
see if these files doe not have the proper protection and tell the user.

[NO NEW TESTS NEEDED]

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

vendor/github.com/containers/storage/pkg/system/xattrs_linux.go

@@ -13,6 +13,9 @@ const (
 
 	// Operation not supported
 	EOPNOTSUPP unix.Errno = unix.EOPNOTSUPP
+
+	// Value is too small or too large for maximum size allowed
+	EOVERFLOW unix.Errno = unix.EOVERFLOW
 )
 
 // Lgetxattr retrieves the value of the extended attribute identified by attr

vendor/github.com/containers/storage/pkg/system/xattrs_unsupported.go

@@ -10,6 +10,9 @@ const (
 
 	// Operation not supported
 	EOPNOTSUPP syscall.Errno = syscall.Errno(0)
+
+	// Value is too small or too large for maximum size allowed
+	EOVERFLOW syscall.Errno = syscall.Errno(0)
 )
 
 // Lgetxattr is not supported on platforms other than linux.