Review Request: 8007093: build-infra: Make should fail if spec is older than configure files

[Tim Bell]

Hi Erik:

> Adding a make rule for the spec file that depends on the autoconf 
> source files and which will always fail if triggered. This guards from 
> running make with an out of date configuration.
>
> http://cr.openjdk.java.net/~erikj/8007093/webrev.root.01/

Looks good.

Tim