RFR: 8303942: os::write should write completely [v8]

[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

Afshin Zafari has updated the pull request incrementally with one additional commit since the last revision:

  eddadeef1b8faa068ffc5cf479c943beeccae0c7

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/13750/files
  - new: https://git.openjdk.org/jdk/pull/13750/files/eddadeef..f0d4db5e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13750&range=07
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13750&range=06-07

  Stats: 9 lines in 1 file changed: 8 ins; 0 del; 1 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