RFR: 8241827: JFR: TestVMInfoEvent.java requires SerialGC

[Stefan Karlsson]

Hi all,

Please review this tiny patch to @require the SerialGC.

https://cr.openjdk.java.net/~stefank/8241827/webrev.01/
https://bugs.openjdk.java.net/browse/JDK-8241827

The test spawns a JVM using the SerialGC. If the test is run with any 
other GC it fails.

Thanks,
StefanK