RFR: JDK-8295710 : unify os::dll_file_extension [v2]

[Matthias Baesken]

> The os::dll_file_extension() function could be unified for the different OS platforms.

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

  Remove os::dll_file_extension

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/10782/files
  - new: https://git.openjdk.org/jdk/pull/10782/files/c533cd24..76a230e9

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10782&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10782&range=00-01

  Stats: 3 lines in 2 files changed: 0 ins; 2 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/10782.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10782/head:pull/10782

PR: https://git.openjdk.org/jdk/pull/10782