[lld-macho] Disable objc test on 32-bit ARM targets

lld/test/MachO/objc-relative-method-lists-simple.s fails on AArch64
hosts running 32-bit ARM binaries, such as
armv8l-unknown-linux-gnueabihf.

Disable the test on the failing targets for now, to keep the
buildbots passing.

GitOrigin-RevId: 6b95747087032e8f86af64325780d8471e6fce58
diff --git a/test/MachO/objc-relative-method-lists-simple.s b/test/MachO/objc-relative-method-lists-simple.s
index 5a77085..9f54b5a 100644
--- a/test/MachO/objc-relative-method-lists-simple.s
+++ b/test/MachO/objc-relative-method-lists-simple.s
@@ -1,4 +1,5 @@
 # REQUIRES: aarch64
+# UNSUPPORTED: target=arm{{.*}}-unknown-linux-gnueabihf
 # RUN: rm -rf %t; split-file %s %t && cd %t
 
 ## Compile a64_rel_dylib.o