caches: disable XML2 explicitly

When cross-compiling to ARM64, we would accidentally enable libxml2
support even if the library was unavailable.  This would result in build
failures.

Author: compnerd

cmake/caches/Windows-arm64.cmake

@@ -68,6 +68,7 @@ set(LLDB_ALLOW_STATIC_BINDINGS YES CACHE BOOL "")
 set(LLDB_USE_STATIC_BINDINGS YES CACHE BOOL "")
 set(LLDB_ENABLE_PYTHON YES CACHE BOOL "")
 set(LLDB_EMBED_PYTHON_HOME NO CACHE BOOL "")
+set(LLDB_ENABLE_LIBXML2 NO CACHE BOOL "")
 
 # This requires perl which may not be available on Windows
 set(SWIFT_INCLUDE_DOCS NO CACHE BOOL "")