[libc++] Mark libcpp_deallocate.sh.cpp as UNSUPPORTED instead of XFAIL on AppleClang 9

Some minor versions of AppleClang 9 appear not to fail the test. It's
such a mess that the only sane thing to do is to mark the test as
UNSUPPORTED.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@366606 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/libcxx/language.support/support.dynamic/libcpp_deallocate.sh.cpp b/test/libcxx/language.support/support.dynamic/libcpp_deallocate.sh.cpp
index af214ea..970b7fc 100644
--- a/test/libcxx/language.support/support.dynamic/libcpp_deallocate.sh.cpp
+++ b/test/libcxx/language.support/support.dynamic/libcpp_deallocate.sh.cpp
@@ -32,7 +32,7 @@
 
 // AppleClang < 10 incorrectly warns that aligned allocation is not supported
 // even when it is supported.
-// XFAIL: apple-clang-9
+// UNSUPPORTED: apple-clang-9
 
 // XFAIL: sanitizer-new-delete, ubsan