RFR: JDK-8301495: Replace NULL with nullptr in cpu/ppc [v2]

[Johan Sjölen]

> Hi, this PR changes all occurrences of NULL to nullptr for the subdirectory cpu/ppc. Unfortunately the script that does the change isn't perfect, and so we
> need to comb through these manually to make sure nothing has gone wrong. I also review these changes but things slip past my eyes sometimes.
> 
> Here are some typical things to look out for:
> 
> 1. No changes but copyright header changed (probably because I reverted some changes but forgot the copyright).
> 2. Macros having their NULL changed to nullptr, these are added to the script when I find them. They should be NULL.
> 3. nullptr in comments and logs. We try to use lower case "null" in these cases as it reads better. An exception is made when code expressions are in a comment.
> 
> An example of this:
> 
> ```c++
> // This function returns null
> void* ret_null();
> // This function returns true if *x == nullptr
> bool is_nullptr(void** x);
> 
> 
> Note how `nullptr` participates in a code expression here, we really are talking about the specific value `nullptr`.
> 
> Thanks!

Johan Sjölen has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains seven commits:

 - Merge remote-tracking branch 'origin/master' into JDK-8301495
 - Merge remote-tracking branch 'origin/master' into JDK-8301495
 - Revert change in file
 - Fixes
 - Merge remote-tracking branch 'origin/master' into JDK-8301495
 - reinrich suggestions
 -  Replace NULL with nullptr in cpu/ppc

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

Changes: https://git.openjdk.org/jdk/pull/12323/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12323&range=01
  Stats: 381 lines in 51 files changed: 0 ins; 0 del; 381 mod
  Patch: https://git.openjdk.org/jdk/pull/12323.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/12323/head:pull/12323

PR: https://git.openjdk.org/jdk/pull/12323