RFR: 8234020: Remove FullGCCount_lock

Mon Apr 26 14:12:26 UTC 2021

On Sun, 25 Apr 2021 19:44:50 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Remove an unused method and unnecessary synchronization in Serial GC.

Looks good, but please also remove:
https://github.com/openjdk/jdk/blob/536cde177986a03e16bb3604e88bc35a6f39bec2/src/hotspot/share/runtime/mutexLocker.cpp#L75

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Changes requested by sjohanss (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/3679