RFR: 8293245: x86_64: Extract Adler32 stub implementation into stubGenerator_x86_64_adler.cpp

[Vladimir Ivanov]

Extract Adler32 stub implementation into a dedicated file (`stubGenerator_x86_64_adler.cpp`).

Minor cleanups:
  * got rid of `updateBytesAdler32()` by manually inlining it into  `generate_updateBytesAdler32()`
  * unified usage of `r14` as a scratch register
  * added 32-byte alignment for the constants

Testing: hs-tier1 - hs-tier4

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Depends on: https://git.openjdk.org/jdk/pull/10111

Commit messages:
 - Move Adler stub definitions into stubGenerator_x86_64_adler.cpp

Changes: https://git.openjdk.org/jdk/pull/10126/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10126&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8293245
  Stats: 542 lines in 6 files changed: 268 ins; 274 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/10126.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10126/head:pull/10126

PR: https://git.openjdk.org/jdk/pull/10126