all: link to https instead of http

The one in misc/makerelease/makerelease.go is particularly bad and
probably warrants rotating our keys.

I didn't update old weekly notes, and reverted some changes involving
test code for now, since we're late in the Go 1.5 freeze. Otherwise,
the rest are all auto-generated changes, and all manually reviewed.

Change-Id: Ia2753576ab5d64826a167d259f48a2f50508792d
Reviewed-on: https://go-review.googlesource.com/12048
Reviewed-by: Rob Pike <r@golang.org>

src/runtime/runtime2.go

@@ -496,7 +496,7 @@ const (
 )
 
 // Layout of in-memory per-function information prepared by linker
-// See http://golang.org/s/go12symtab.
+// See https://golang.org/s/go12symtab.
 // Keep in sync with linker
 // and with package debug/gosym and with symtab.go in package runtime.
 type _func struct {