*: 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/node/build/mkimage/main.go b/metropolis/node/build/mkimage/main.go
index 5546055..f41d643 100644
--- a/metropolis/node/build/mkimage/main.go
+++ b/metropolis/node/build/mkimage/main.go
@@ -84,7 +84,8 @@
 	}
 
 	table := &gpt.Table{
-		// This is appropriate at least for virtio disks. Might need to be adjusted for real ones.
+		// This is appropriate at least for virtio disks. Might need to be
+		// adjusted for real ones.
 		LogicalSectorSize:  512,
 		PhysicalSectorSize: 512,
 		ProtectiveMBR:      true,
@@ -165,7 +166,8 @@
 		log.Fatalf("os.Open(%q): %v", src, err)
 	}
 	defer source.Close()
-	// If this is streamed (e.g. using io.Copy) it exposes a bug in diskfs, so do it in one go.
+	// If this is streamed (e.g. using io.Copy) it exposes a bug in diskfs, so
+	// do it in one go.
 	data, err := ioutil.ReadAll(source)
 	if err != nil {
 		log.Fatalf("Reading %q: %v", src, err)