[jdk11u-dev] RFR: 8255254: Split os::reserve_memory and os::map_memory_to_file interfaces

[Vladimir Kempik]

Please review this backport of JDK-8255254 to jdk11u-dev.
This is a prerequest for mac-aarch64 and MAP_JIT support.

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Commit messages:
 - 8255254: Split os::reserve_memory and os::map_memory_to_file interfaces
 - Fix up windows
 - 8253638: Cleanup os::reserve_memory and remove MAP_FIXED

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/577/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=577&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8255254
  Stats: 289 lines in 18 files changed: 102 ins; 100 del; 87 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/577.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/577/head:pull/577

PR: https://git.openjdk.java.net/jdk11u-dev/pull/577