*: reflow comments to 80 characters

This reformats the entire Metropolis codebase to have comments no longer
than 80 characters, implementing CR/66.

This has been done half manually, as we don't have a good integration
between commentwrap/Bazel, but that can be implemented if we decide to
go for this tool/limit.

Change-Id: If1fff0b093ef806f5dc00551c11506e8290379d0
diff --git a/metropolis/pkg/erofs/defs_test.go b/metropolis/pkg/erofs/defs_test.go
index e32e155..1d31bff 100644
--- a/metropolis/pkg/erofs/defs_test.go
+++ b/metropolis/pkg/erofs/defs_test.go
@@ -24,8 +24,8 @@
 	"github.com/stretchr/testify/assert"
 )
 
-// These test that the specified structures serialize to the same number of bytes as the ones in the
-// EROFS kernel module.
+// These test that the specified structures serialize to the same number of
+// bytes as the ones in the EROFS kernel module.
 
 func TestSuperblockSize(t *testing.T) {
 	var buf bytes.Buffer