java-runtime-headless no longer provided by openjdk-8-jre-headless

[Srdjan Grubor]

On Ubuntu 15.10, version 8u91-b14-0ubuntu4~15.10.1 no longer provides virtual package `java-runtime-headless` while the older version does (8u66-b01-5):

$ apt-cache show openjdk-8-jre-headless | grep 'Provides\|Version'
Version: 8u91-b14-0ubuntu4~15.10.1
Provides: java2-runtime-headless, java5-runtime-headless, java6-runtime-headless, java7-runtime-headless, java8-runtime-headless
Version: 8u66-b01-5
Provides: java-runtime-headless, java2-runtime-headless, java5-runtime-headless, java6-runtime-headless, java7-runtime-headless, java8-runtime-headless

...
Package java-runtime-headless is a virtual package provided by:
  openjdk-6-jre-headless 6b38-1.13.10-0ubuntu0.15.10.1
  openjdk-7-jre-headless 7u101-2.6.6-0ubuntu0.15.10.1
  gcj-4.8-jre-headless 4.8.5-1ubuntu1
  gcj-jre-headless 4:5.2.1-3ubuntu1
  gcj-5-jre-headless 5.2.1-22ubuntu2
  gcj-4.9-jre-headless 4.9.3-5ubuntu1
  default-jre-headless 2:1.7-52
You should explicitly select one to install.

E: Package 'java-runtime-headless' has no installation candidate
...

This breaks many programs that have `java-runtime-headless` as a requirement.

[Simon Déziel (sdeziel)]

This change was done in https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=815475 to comply with this policy: https://www.debian.org/doc/packaging-manuals/java-policy/ch02.html#policy-programs

As such, marking as invalid.