Auto merge of #18220 - cosmo0920:detect-aarch64-in-mach, r=jdm

Handle aarch64 cpu_type in mach

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This is a PR for #18217.

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- [ ] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

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python/servo/util.py

@@ -67,6 +67,8 @@ def host_triple():
         cpu_type = "x86_64"
     elif cpu_type == "arm":
         cpu_type = "arm"
+    elif cpu_type == "aarch64":
+        cpu_type = "aarch64"
     else:
         cpu_type = "unknown"