RFR: 8243315: ParallelScavengeHeap::initialize() passes GenAlignment as page size to os::trace_page_sizes instead of actual page size [v5]

[Joakim Nordström]

> ### Description
> The logging for reserved heap space, printed the `GenAlignment` value instead of page size.
> Before:
> <pre>
> [0.369s][info][gc      ] Using Parallel
> [0.374s][info][pagesize] Heap:  min=2M max=2M base=0x00000000ffe00000 <b>page_size=512K</b> size=2M
> </pre>
> Besides changing to display page size using `os::vm_page_size()`, this fix also adds logging of `SpaceAlignment `,`GenAlignment`, and `HeapAlignment`. 
> After:
> <pre>
> [0.367s][info][pagesize] <b>Alignments:  space_align=512K gen_align=512K heap_align=2M</b>
> [0.369s][info][gc      ] Using Parallel
> [0.374s][info][pagesize] Heap:  min=2M max=2M base=0x00000000ffe00000 <b>page_size=4K</b> size=2M
> </pre>
> Please advice whether the added logging of alignments is sufficient or irrelevant. There were no signs of either alignment being logged anywhere.
> ### Testing
> - Tested manually, and logs are showing with arguments <code>-Xlog:pagesize=info -XX:+UseParallelGC</code>
> - Tested Tier1, Tier2, Tier3.

Joakim Nordström has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains eight commits:

 - Merge remote-tracking branch 'origin/master' into JBS-8180069
 - Moved helper function actual_reserved_page_size to ReservedSpace
 - Changed so heap info is logged as heap info and not gc_specific
 - Fixed whitespaces.
 - Added ParallelInitLogger with alignment logging
 - Added ParallelInitLogger with alignment logging
 - Added logging method that logs actual reserved page sizes, and not just vm_page_size.
 - 8180069: ParallelScavengeHeap::initialize() passes GenAlignment as page size to os::trace_page_sizes instead of actual page size

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

Changes: https://git.openjdk.java.net/jdk/pull/1161/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1161&range=04
  Stats: 145 lines in 7 files changed: 117 ins; 24 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1161.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1161/head:pull/1161

PR: https://git.openjdk.java.net/jdk/pull/1161