[llvm][ExecutionEngine] Don't try to run tests on ARM64/Windows on Arm

We use CMAKE_SYSTEM_PROCESSOR to set the host_arch lit feature.
This is going to be the same value as CMAKE_HOST_SYSTEM_PROCESSOR,
which on windows is set to the value of the PROCESSOR_ARCHITECTURE
environment variable.

https://cmake.org/cmake/help/latest/variable/CMAKE_HOST_SYSTEM_PROCESSOR.html#cmake-host-system-processor

On Windows on Arm this is "ARM64", not "AArch64" as we currently
look for.

https://docs.microsoft.com/en-us/windows/win32/winprog64/wow64-implementation-details#environment-variables

Add ARM64 to the unsupported list.

Reviewed By: lhames

Differential Revision: https://reviews.llvm.org/D107361

llvm/test/ExecutionEngine/lit.local.cfg

@@ -1,4 +1,4 @@
-if config.root.host_arch in ['Sparc', 'PowerPC', 'AArch64', 'SystemZ']:
+if config.root.host_arch in ['Sparc', 'PowerPC', 'AArch64', 'ARM64', 'SystemZ']:
     config.unsupported = True
 
 # CMake and autoconf diverge in naming or host_arch