RFR: JDK-8312013: avoid UnixConstants.java.template warning: '__linux__' is not defined on AIX [v2]

[Matthias Baesken]

> We run into this build warning on AIX :
> /jdk/src/java.base/unix/classes/sun/nio/fs/UnixConstants.java.template:127:7: warning: '__linux__' is not defined, evaluates to 0 [-Wundef]
> #elif __linux__
> 1 warning generated.
> 
> Looks like the preprocessor check should be adjusted, because the macro is not present on non-Linux systems.

Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:

  adjust COPYRIGHT headers

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/14864/files
  - new: https://git.openjdk.org/jdk/pull/14864/files/e53bf994..894c6bcb

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14864&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14864&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/14864.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14864/head:pull/14864

PR: https://git.openjdk.org/jdk/pull/14864