[jdk17u-dev] RFR: 8299971: Remove metaprogramming/conditional.hpp

[George Adams]

Backport applies cleanly other than the deleted files containing additional commits. Also these two files no longer exist in 17u-dev:

- `src/hotspot/share/runtime/continuationFreezeThaw.cpp`
- `src/hotspot/share/utilities/moveBits.hpp`

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Commit messages:
 - Backport 4c1e66e0abe9e379926e555bd651e9fcc5a0e8b6

Changes: https://git.openjdk.org/jdk17u-dev/pull/2690/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2690&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8299971
  Stats: 86 lines in 8 files changed: 4 ins; 60 del; 22 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2690.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2690/head:pull/2690

PR: https://git.openjdk.org/jdk17u-dev/pull/2690