all: correct typos in comments

Change-Id: Idc75240e5546be2f2b091878910339b4967c93c7
GitHub-Last-Rev: c78560c06fce951fefdb83c2550bc99ca15c48ef
GitHub-Pull-Request: golang/net#166
Reviewed-on: https://go-review.googlesource.com/c/net/+/465715
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
diff --git a/icmp/multipart.go b/icmp/multipart.go
index 5f36675..c7b72bf 100644
--- a/icmp/multipart.go
+++ b/icmp/multipart.go
@@ -33,7 +33,7 @@
 }
 
 // multipartMessageOrigDatagramLen takes b as an original datagram,
-// and returns a required length for a padded orignal datagram in wire
+// and returns a required length for a padded original datagram in wire
 // format.
 func multipartMessageOrigDatagramLen(proto int, b []byte) int {
 	roundup := func(b []byte, align int) int {