cmd/doc: suppresses const blocks that start with unexported names

[dsnet]

Using Go1.5

Given a package of the following:

package foo

const (
    Foo = iota
    Bar
    Baz
)

const (
    unexported = iota
    Exported
    Another
)

const (
    Kilo = 1E3
    Mega = 1E6
    Giga = 1E9
)

The go doc tool prints the following:

package foo // import "."

const Foo = iota ...
const Kilo = 1E3 ...

I expect the following:

package foo // import "."

const Foo = iota ...
const Exported ...
const Kilo = 1E3 ...

The "go doc" tool should not hide the existance of the "Exported" const.

[dsnet]

This may be related to #11705, but I'm not sure what exactly the author is expecting in that issue.

Also, I would be interested in fixing this issue if nobody wants to take it.

[gopherbot]

CL https://golang.org/cl/14780 mentions this issue.