RFR: 8255225: compiler/aot tests fail on Windows with NPE during artifact resolution

[Aleksey Shipilev]

Bisection shows it started to happen after [JDK-8253660](https://bugs.openjdk.java.net/browse/JDK-8253660). I believe `toString()` there is not very resilient in the face of `null` causes.

Example output:
$ make run-test TEST=compiler/aot

STDERR:
java.lang.NullPointerException: Cannot invoke "java.lang.Throwable.getCause()" because "<local1>" is null
at jdk.test.lib.artifacts.ArtifactResolverException.getRootCause(ArtifactResolverException.java:22)
at jdk.test.lib.artifacts.ArtifactResolverException.toString(ArtifactResolverException.java:17)
...
at compiler.aot.AotCompiler.resolveLinker(AotCompiler.java:270)
at compiler.aot.AotCompiler.launchCompiler(AotCompiler.java:112)
at compiler.aot.AotCompiler.main(AotCompiler.java:78)
...

...and since it is a part of this block:

        } catch (ArtifactResolverException e) {
            System.err.println("artifact resolution error: " + e); // <--- calling to broken toString() here
            e.printStackTrace(System.err);
            // let jaotc try to find linker
            return null;
        }

...we never actually get to `// let jaotc try to find linker` part, and that is why I suspect it causes Windows x86_64 tier1/compiler failures in GitHub workflows. See below, `Windows tier1/compiler` tests are now passing. (There are some infra failures in other places on Windows, though).

-------------

Commit messages:
 - 8255225: compiler/aot tests fail on Windows with NPE during artifact resolution

Changes: https://git.openjdk.java.net/jdk/pull/800/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=800&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8255225
  Stats: 13 lines in 1 file changed: 8 ins; 0 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/800.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/800/head:pull/800

PR: https://git.openjdk.java.net/jdk/pull/800