disable use-std-span.swift for macOS

Author: hnrklssn

test/Interop/Cxx/stdlib/use-std-span.swift

@@ -4,6 +4,9 @@
 // TODO: test failed in Windows PR testing: rdar://144384453
 // UNSUPPORTED: OS=windows-msvc
 
+// TODO: test failed in macOS PR testing but passes locally: rdar://163049442
+// UNSUPPORTED: OS=macosx
+
 // REQUIRES: executable_test
 // REQUIRES: std_span