[libc++] Another Apple CI quick-fix.

Like #135202 this fixes another issue after the XCode update.

Author: mordante

libcxxabi/test/uncaught_exception.pass.cpp

@@ -6,6 +6,9 @@
 //
 //===----------------------------------------------------------------------===//
 
+// TODO(mordante) Investigate
+// UNSUPPORTED: apple-clang
+
 // UNSUPPORTED: no-exceptions
 
 // This tests that libc++abi still provides __cxa_uncaught_exception() for