[11u] RFR 8229773: Resolve permissions for code source URLs lazily

[Langer, Christoph]

Hi,

please review the backport for JDK-8229773: Resolve permissions for code source URLs lazily to OpenJDK11 updates.

Bug: https://bugs.openjdk.java.net/browse/JDK-8229773
Webrev: http://cr.openjdk.java.net/~clanger/webrevs/8229773.11u-dev.0/
Original Change: https://hg.openjdk.java.net/jdk/jdk/rev/1b6806340400

The patch did not apply cleanly and I had to resolve
src/java.base/share/classes/java/lang/System.java: imports and the hunk about "// ensure the default file system is initialized"
src/java.base/share/classes/jdk/internal/loader/BuiltinClassLoader.java: import statements

With these modifications, the patch applies and regression testing does not show findings.

Thanks
Christoph