RFR: 8303942: FileMapInfo::write_bytes aborts on a short os::write

[Afshin Zafari]

`os::write` is implemented using loops until the whole bytes are written. All uses of `os::write` in a loop are changed to single call. 
Platform dependent versions of the `os::write` are also renamed and moved to private sections accordingly.
Wrong uses/interpretations of return values from `os::write` in JFR code are corrected.

###Test
local: hotspot tier1
mach5: tiers 1-5

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Commit messages:
 - 8303942: FileMapInfo::write_bytes aborts on a short os::write

Changes: https://git.openjdk.org/jdk/pull/13750/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13750&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8303942
  Stats: 71 lines in 9 files changed: 26 ins; 19 del; 26 mod
  Patch: https://git.openjdk.org/jdk/pull/13750.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13750/head:pull/13750

PR: https://git.openjdk.org/jdk/pull/13750