RFR: 8260941: Remove the conc_scan parameter for CardTable [v2]

[Thomas Schatzl]

> Hi,
> 
>   can I have reviews for this removal of the last(?) CMS-specific code in CardTable, namely some provision to indicate that cards are being scanned concurrently in Serial/Parallel GC barrier code?
> 
> The change simply follows the predicate into Serial/Parallel GC code which always returns false for them and removes that code.
> 
> In the review for JDK-8234534 I mentioned that I split this out due to unexplainable errors; testing tier1-5 three times showed none of that any more (after updating to latest code).
> 
> This change has only been built on Oracle-platforms and linux-x86 via github actions (https://github.com/tschatzl/jdk/actions/runs/539993964), so I would like to kindly ask maintainers of the others to compile and report issues (32 bit ARM, PPC etc).
> 
> Testing: tier1-5

Thomas Schatzl has updated the pull request incrementally with one additional commit since the last revision:

  kbarrett review

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/2425/files
  - new: https://git.openjdk.java.net/jdk/pull/2425/files/5db8cbe6..9c0129d3

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=2425&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=2425&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2425.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2425/head:pull/2425

PR: https://git.openjdk.java.net/jdk/pull/2425