Allow internal JDK builds to be used with Substrate.

[johanvos]

When building the JDK from sources, by default the version name will contain the "internal-" String. This patch allows JDK versions containing this "internal-" String to be used as sources for GraalVM builds

Fix for #1201

Issue

Fixes #

Progress

• [ ] Change must not contain extraneous whitespace
• [ ] License header year is updated, if required
• [ ] Verify the contributor has signed Gluon Individual Contributor License Agreement (CLA)