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

[Erik Joelsson]

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make with an out of date configuration.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/

/Erik