[jdk7u] RFR: 8285445: cannot open file "NUL:"

[Olga Mikhaltsova]

I'd like to backport JDK-8285445 to jdk7u.

The patch applied not cleanly due to the directory structure differences:
`src/java.base/windows/classes/java/io/WinNTFileSystem.java`-> `jdk/src/windows/classes/java/io/Win32FileSystem.java`
`test/jdk/java/io/FileOutputStream/OpenNUL.java`-> `jdk/test/java/io/FileOutputStream/OpenNUL.java`

Tested manually as follow:
`$JTREG_HOME/bin/jtreg -jdk:$BUILD_HOME /cygdrive/c/projects/jdk7u-fork/jdk/test/java/io/`
No regression in the above tests' group.

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Commit messages:
 - Backport 03cbb48e6a1d806f204a39bbdbb4bc9be9e57a41

Changes: https://git.openjdk.org/jdk7u/pull/9/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk7u&pr=9&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8285445
  Stats: 57 lines in 2 files changed: 52 ins; 1 del; 4 mod
  Patch: https://git.openjdk.org/jdk7u/pull/9.diff
  Fetch: git fetch https://git.openjdk.org/jdk7u pull/9/head:pull/9

PR: https://git.openjdk.org/jdk7u/pull/9