[JITLink] Disable the all-load- tests on Windows/arm64.

We don't have a JITLink Windows/arm64 backend yet, so disable these tests
there.
diff --git a/llvm/test/ExecutionEngine/JITLink/Generic/all-load-multifile-archive-with-duplicate-member-filenames.test b/llvm/test/ExecutionEngine/JITLink/Generic/all-load-multifile-archive-with-duplicate-member-filenames.test
index edcae52..1102339 100644
--- a/llvm/test/ExecutionEngine/JITLink/Generic/all-load-multifile-archive-with-duplicate-member-filenames.test
+++ b/llvm/test/ExecutionEngine/JITLink/Generic/all-load-multifile-archive-with-duplicate-member-filenames.test
@@ -7,6 +7,9 @@
 # RUN: llvm-jitlink -all_load -show-init-es -noexec %t/main.o -L%t -lFoo \
 # RUN:     | FileCheck %s
 #
+# FIXME: Enable this test on Windows/arm64 once that backend is available.
+# UNSUPPORTED: target=aarch64-pc-windows-{{.*}}
+#
 # Check that synthesized archive member names are unambiguous, even if an
 # archive contains multiple files with the same name.
 #
diff --git a/llvm/test/ExecutionEngine/JITLink/Generic/all-load-multifile-archive.test b/llvm/test/ExecutionEngine/JITLink/Generic/all-load-multifile-archive.test
index 576f698..22c60eb 100644
--- a/llvm/test/ExecutionEngine/JITLink/Generic/all-load-multifile-archive.test
+++ b/llvm/test/ExecutionEngine/JITLink/Generic/all-load-multifile-archive.test
@@ -6,6 +6,9 @@
 # RUN: llvm-jitlink -noexec -all_load -show-init-es %t/main.o -L%t -lFoo \
 # RUN:     | FileCheck %s
 #
+# FIXME: Enable this test on Windows/arm64 once that backend is available.
+# UNSUPPORTED: target=aarch64-pc-windows-{{.*}}
+#
 # Check that the llvm-jitlink -all-load option loads all members of
 # multi-file archives.
 #