RFR: 8263354: Accumulated C2 code cleanups [v2]

[Pengfei Li]

> This is a trivial patch to cleanup C2 code at several places, including
> 
> - Remove duplicated node enumerations of MinV & MaxV in adlc functions
> - Use "1<<X" to define LoopNode flags, like other C2 flag definitions
> - Unify macro names in aarch64_sve_ad.m4: UNPREDICATE -> UNPREDICATED
> - Delete redundant empty lines in aarch64_sve.ad
> 
> Tier1 tests passed.

Pengfei Li has updated the pull request incrementally with one additional commit since the last revision:

  Update copyright year

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/2934/files
  - new: https://git.openjdk.java.net/jdk/pull/2934/files/cefe164f..4965b425

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=2934&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=2934&range=00-01

  Stats: 4 lines in 2 files changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2934.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2934/head:pull/2934

PR: https://git.openjdk.java.net/jdk/pull/2934