[Test] Disable witness-layout-opts-irgen.swift on iOS simulators, not XFAIL, since it will probably pass on 64-bit simulators.

Author: mikeash

test/Interop/Cxx/value-witness-table/witness-layout-opts-irgen.swift

@@ -8,7 +8,7 @@
 // XFAIL: OS=windows-msvc
 
 // Failing on i386 simulator, disable for now. rdar://73829982
-// XFAIL: DARWIN_SIMULATOR=ios
+// UNSUPPORTED: DARWIN_SIMULATOR=ios
 
 import WitnessLayoutOpts