RFR(XXS): 8242792: interval < flushInterval is always false in jdk.jfr.internal.RequestEngine#setFlushInterval

[Denghui Dong]

Hi team,

Could you please review this small patch?

JBS: https://bugs.openjdk.java.net/browse/JDK-8242792
webrev: http://cr.openjdk.java.net/~ddong/8242792/webrev.00/

Summary:
the condition interval < flushInterval is always false in jdk.jfr.internal.RequestEngine#setFlushInterval,
and I also fix a typo in jdk/jfr/internal/JVM.java

Thanks,
Denghui Dong