[llvm][llvm-jitlink] Disable test on Windows on Arm

This fails on one of our bots:
https://lab.llvm.org/buildbot/#/builders/120/builds/6309

llvm-jitlink error: Unsupported target machine architecture in COFF object

The other bot doesn't run the test at all it seems but I can't explain
why. It's also possible that I'm mistaken and the mostly native but still
"cross compiling" setup we have on WoA means an x86 object is produced sometimes
(perhaps because a default triple is still x86).