[LIT] Add AArch64/Windows to LP64 feature

[omjavaid]

Summary

This patch adds AArch64 to the LP64 feature to avoid running LLP64
incompatible test on AArch64/Windows platform.

[DavidSpickett]

LGTM

clang/test/lit.cfg.py

 if os.path.exists('/dev/fd/0') and sys.platform not in ['cygwin']:
     config.available_features.add('dev-fd-fs')
 
 # Set on native MS environment.
 if re.match(r'.*-(windows-msvc)$', config.target_triple):
     config.available_features.add('ms-sdk')
 
 # [PR8833] LLP64-incompatible tests
-if not re.match(r'^x86_64.*-(windows-msvc|windows-gnu)$', config.target_triple):
+if not re.match(r'^(aarch64|x86_64).*-(windows-msvc|windows-gnu)$', config.target_triple):
     config.available_features.add('LP64')
 
 # Tests that are specific to the Apple Silicon macOS.
 if re.match(r'^arm64(e)?-apple-(macos|darwin)', config.target_triple):
     config.available_features.add('apple-silicon-mac')
 
 # [PR18856] Depends to remove opened file. On win32, a file could be removed
 # only if all handles were closed.