RFR: 8293064: Remove unused NET_xxx functions

Mon Sep 19 18:37:56 UTC 2022

On Mon, 19 Sep 2022 14:32:24 GMT, Darragh Clarke <duke at openjdk.org> wrote:

> No tests were affected so this is purely a removal PR apart from updating copyright headers.
> I ran tests for Tier 1,2&3 and everything seems to be passing

The changes looks good to me with few additional changes needed on Linux platform: 
- `NET_SetTrafficClass`: It was discovered by invoking linker with `--print-gc-sections` option on a Linux-x64 platform. Header file: `net_util_md.h` Source file: `net_util_md.c`, both located in `src/java.base/unix/native/libnet`.
- `NET_ThrowCurrent` on Linux (as already spotted by Daniel). It needs to be removed from `src/java.base/[unix|windows]/native/libnet/net_util_md.c`

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Changes requested by aefimov (Committer).

PR: https://git.openjdk.org/jdk/pull/10343