RFR: 8344568: Renaming ceil_log2 to log2i_ceil

[Sonia Zaldana Calles]

Hi all, 

This PR addresses [8344568](https://bugs.openjdk.org/browse/JDK-8344568). Should be a straightforward rename and cleanup. 

Thanks, 
Sonia

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Commit messages:
 - 8344568: Renaming ceil_log2 to log2i_ceil

Changes: https://git.openjdk.org/jdk/pull/22279/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22279&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8344568
  Stats: 43 lines in 7 files changed: 7 ins; 7 del; 29 mod
  Patch: https://git.openjdk.org/jdk/pull/22279.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22279/head:pull/22279

PR: https://git.openjdk.org/jdk/pull/22279