CGO_LDFLAGS_ALLOW as go cmd build flag

[suizman]

It's really painful to use environment variable to pass allowed CGO flags.
It would be great to be able to pass this stuff as an build flag.

Eg:
go build -cgo-ldflags-allow '.*'

[ianlancetaylor]

Use a shell script or use go env -w. I don't think we need two ways to do this.

[suizman]

OK @ianlancetaylor, i'll give it a try, but it seams that go env -w is on 1.13.0 beta.

[andybons]

@suizman thanks for the issue. Yes you're correct about go env -w being introduced in 1.13. Sorry for the inconvenience.

[suizman]

Thanks @andybons