RFR: Fix recent merge errors [v2]

[Aleksey Shipilev]

> I skipped through current premain-vs-mainline webrev, and noticed a few merge errors.
> 
> `metaspaceShared.cpp` hunks are obvious duplications. I removed the lines that are actually different from mainline.
> 
> ~`compilationPolicy.hpp` hunk is a leftover from AOT Profiling. I remember pointing this out to @veresov during mainline review, and we went into mainline without that extra `notify_all`. We should ditch it in premain too.~ Actually, I see test timeouts when that `notify_all` is removed. Filed [JDK-8358343](https://bugs.openjdk.org/browse/JDK-8358343) to figure it out. Yanked the hunk from this PR.
> 
> Additional testing:
>  - [x] Linux x86_64 server fastdebug, `runtime/cds`

Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:

  Put notify_all back

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

Changes:
  - all: https://git.openjdk.org/leyden/pull/72/files
  - new: https://git.openjdk.org/leyden/pull/72/files/0262c563..ac9c2a78

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=leyden&pr=72&range=01
 - incr: https://webrevs.openjdk.org/?repo=leyden&pr=72&range=00-01

  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/leyden/pull/72.diff
  Fetch: git fetch https://git.openjdk.org/leyden.git pull/72/head:pull/72

PR: https://git.openjdk.org/leyden/pull/72