[test] verify_all_overlays doesn't actually fail on watchOS

Further fix-up for 482d2ba.

Author: jrose-apple

validation-test/SIL/verify_all_overlays.sil

@@ -7,5 +7,5 @@
 // REQUIRES: long_test
 // REQUIRES: nonexecutable_test
 
-// XFAIL: OS=macosx || OS=ios || OS=tvos || OS=watchos
+// XFAIL: OS=macosx || OS=ios || OS=tvos
 // https://bugs.swift.org/browse/SR-9847