RFR: 8315020: The macro definition for LoongArch64 zero build is not accurate. [v2]

[Ao Qi]

> The `LOONGARCH` is not a macro that must be defined. It is not a C/C++ pre-defined macro and is also not pre-defined in libraries such as libffi. We'd better use a macro defined in jdk.

Ao Qi has updated the pull request incrementally with one additional commit since the last revision:

  rename LOONGARCH and move RISCV32 to zero

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/15428/files
  - new: https://git.openjdk.org/jdk/pull/15428/files/e944f3a5..a5b40898

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15428&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15428&range=00-01

  Stats: 5 lines in 2 files changed: 2 ins; 2 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/15428.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15428/head:pull/15428

PR: https://git.openjdk.org/jdk/pull/15428