doc: remove CL 159258 from 1.13 release notes list

It was rolled back.

Change-Id: I8372bb7e11bab7be242f4af7093a73d2fa093067
Reviewed-on: https://go-review.googlesource.com/c/go/+/180760Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

doc/go1.13.html

@@ -95,7 +95,6 @@ TODO; link to <a href="/doc/go1.12#tls_1_3">Go 1.12 notes</a>.
 TODO
 </p>
 
-<!-- CL 159258: https://golang.org/cl/159258: cmd/cgo: use C exact-width integer types to represent Go types -->
 <!-- CL 161904: https://golang.org/cl/161904: cmd/compile: do not export float or complex constants with -asmhdr -->
 <!-- CL 167780: https://golang.org/cl/167780: cmd/compile: rename init function from init.ializers back to init -->
 <!-- CL 170448: https://golang.org/cl/170448: cmd/compile: enable -newescape by default -->