build: use arm64 as DESTCPU for aarch64

[danbev]

On a aarch64 system I can run the complete build with tests without
specifying the Makefile variable DESTCPU.

But when running the tar-headers target DESTCPU is passed to configure:

    $(PYTHON) ./configure \
               --prefix=/ \
               --dest-cpu=$(DESTCPU) \
               ...

The value of DESTCPU in this case will be 'aarch64' which will cause
configure to fail:

configure: error: option --dest-cpu: invalid choice: 'aarch64'
(choose from 'arm', 'arm64', 'ia32', 'mips', 'mipsel', 'mips64el', 'ppc',
'ppc64', 'x32', 'x64', 'x86', 'x86_64', 's390', 's390x')

In the configure script there is a matching of __aarch64__ to arm64:

$ python -c 'from configure import host_arch_cc; print host_arch_cc()'
arm64

In our case it would be nice to have consitent behaviour for both of
these cases on aarch64.

This commit changes DESTCPU to arm64 to be consistent with the
configure script. DESTCPU is used in $(TARBALL)-headers and in
$(BINARYTAR) but I'm not sure about the implications of making the
change purposed and hope others might chime in and provide some
guidance.

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• commit message follows commit guidelines

[nodejs-github-bot]

@danbev build started: https://ci.nodejs.org/blue/organizations/jenkins/node-test-pull-request-lite-pipeline/detail/node-test-pull-request-lite-pipeline/693/pipeline

[danbev]

CI: https://ci.nodejs.org/job/node-test-pull-request/16775/

[danbev]

Re-run of failing node-test-commit-freebsd was successful.

[richardlau]

Ref: #5175

[yselkowitz]

This is only half the change necessary. Further below (around line 750) you also need to:

-ifeq ($(DESTCPU),aarch64)
+ifeq ($(DESTCPU),arm64)

[danbev]

This is only half the change necessary. Further below (around line 750) you also need to

Thanks @yselkowitz! I'll take a closer look at this tomorrow.

[danbev]

CI: https://ci.nodejs.org/job/node-test-pull-request/16889/

[BridgeAR]

@nodejs/build-files PTAL

[addaleax]

CI: https://ci.nodejs.org/job/node-test-pull-request/16914/

[refack]

I don't have enough background, but reading https://stackoverflow.com/a/47274698/27955 makes me think it should be the other way around... (map arm64 to aarch64)

1. https://www.phoronix.com/scan.php?page=news_item&px=MTY5ODk

 With that aligned, within the LLVM code-base the Apple ARM64 back-end was then
 renamed to AArch64 to reflect the official 64-bit ARM architecture title.

2. https://gcc.gnu.org/onlinedocs/gcc/AArch64-Options.html

[yselkowitz]

v8 uses arm64 throughout, as does the kernel and golang for instance. While aarch64 is more canonical, I'm in no position to change any of those and doing so would be much more extensive than simply fixing DESTCPU.

[gdams]

I'm not going to block this change but IMO we should be using aarch64 instead of arm64 to be consistent with most other packages. AFAIK arm64 is something that Apple invented and never properly got adopted by anyone else.

[refack]

v8 uses arm64 throughout

Since node is highly dependant on V8, let's go with arm64...

[addaleax]

Resume CI: https://ci.nodejs.org/job/node-test-pull-request/16939/

[danbev]

Landed in d7d3bf5.