RFR: 8254560: Shenandoah: Concurrent Strong Roots logging is incorrect

[Aleksey Shipilev]

Look:

[1382.171s][info][gc,stats] Concurrent Strong Roots            1059 us, parallelism: 2.12x
[1382.171s][info][gc,stats] Rendezvous                         2246 us
[1382.171s][info][gc,stats]   CSR: Code Cache Roots              84 us, workers (us):  14,  17,  13,  14,  10,   6,
4,   5,  [1382.171s][info][gc,stats]   CSR: VM Weak Roots               2162 us, workers (us): ---, ---, 905, ---, ---,
388, 383, 486,

There should be `CSR: <total>`, but `Rendezvous` is in its place.

Testing:
  - [x] Eyeballing `-Xlog:gc+stats` on Linux x86_64

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

Commit messages:
 - 8254560: Shenandoah: Concurrent Strong Roots logging is incorrect

Changes: https://git.openjdk.java.net/jdk/pull/599/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=599&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8254560
  Stats: 2 lines in 1 file changed: 1 ins; 1 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/599.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/599/head:pull/599

PR: https://git.openjdk.java.net/jdk/pull/599