RFR: 7856: Fix errors in Eclipse projects after JMC-7769

[Marcus Hirt]

On Fri, 15 Jul 2022 21:23:34 GMT, Christoph Langer <clanger at openjdk.org> wrote:

> [JMC-7769](https://bugs.openjdk.org/browse/JMC-7769) cleaned up the project layout for missioncontrol core, especially the test projects.
> However, after that patch, an Eclipse IDE setup shows errors in test projects of the application, e.g. in org.openjdk.jmc.rjmx.test.
> 
> This is caused by an issue in project setup of core/tests/org.openjdk.jmc.common.test, which is a prerequisite to some other test projects.
> Class files are generated into the target/test-classes folder but Eclipse only exposes target/classes to dependent projects.
> 
> The fix is to set up org.openjdk.jmc.common.test like a general library project, only using src/main/java -> target/classes.
> 
> Because it is a module of missioncontrol.core.tests, the property `fail.if.no.tests=false` needs to be set, otherwise the build fails because tests would be expected.

Marked as reviewed by hirt (Lead).

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PR: https://git.openjdk.org/jmc/pull/413