RFR: JDK-8263068: Rename safefetch.hpp to safefetch.inline.hpp

[Anton Kozlov]

Please review a trivial renaming of safefetch.hpp to safefetch.inline.hpp. It is a preparation to fix for @stefank note https://github.com/openjdk/jdk/pull/2200#discussion_r572707505. I'm going to rename threadWXSetters.hpp to threadWXSetters.inline.hpp and threadWXSetters header is needed for safefetch inline functions implementation.

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Commit messages:
 - Rename safefetch.hpp -> safefetch.inline.hpp

Changes: https://git.openjdk.java.net/jdk/pull/2844/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2844&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8263068
  Stats: 12 lines in 10 files changed: 0 ins; 0 del; 12 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2844.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2844/head:pull/2844

PR: https://git.openjdk.java.net/jdk/pull/2844