Bug ID: JDK-8295395 Linux Alpha Zero builds fail after JDK-8292591

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JDK 20
20 b20Fixed

```
* For target hotspot_variant-zero_libjvm_objs_systemMemoryBarrier_linux.o:
cc1plus: warning: -fstack-protector not supported for this target
src/hotspot/os/linux/systemMemoryBarrier_linux.cpp:43:4: error: #error define SYS_membarrier for the arch
   #error define SYS_membarrier for the arch
    ^~~~~
src/hotspot/os/linux/systemMemoryBarrier_linux.cpp: In function 'int membarrier(int, unsigned int, int)':
src/hotspot/os/linux/systemMemoryBarrier_linux.cpp:65:18: error: 'SYS_membarrier' was not declared in this scope
   return syscall(SYS_membarrier, cmd, flags, cpu_id); // cpu_id only on >= 5.10
                  ^~~~~~~~~~~~~~
At global scope:
```

This only fails with Debian 9 (GCC 6, GLIBC 2.24, Linux 4.9), more recent versions have the definition.

There:

```
/usr/alpha-linux-gnu/include/bits/syscall.h
898:#ifdef __NR_membarrier
899:# define SYS_membarrier __NR_membarrier

/usr/alpha-linux-gnu/include/asm-generic/unistd.h
755:#define __NR_membarrier 283
756:__SYSCALL(__NR_membarrier, sys_membarrier)
```

We can just add the fallback definition in the relevant block.

Changeset: b269c51d Author: Aleksey Shipilev <shade@openjdk.org> Date: 2022-10-17 17:56:49 +0000 URL: https://git.openjdk.org/jdk/commit/b269c51d10c353d9b7143b2239beb23c01352182

17-10-2022

A pull request was submitted for review. URL: https://git.openjdk.org/jdk/pull/10721 Date: 2022-10-17 07:44:55 +0000

17-10-2022

Relates :	JDK-8332253 - Linux arm32 build fails after 8292591
Relates :	JDK-8292591 - Experimentally add back barrier-less Java thread transitions