Fix stack_test.cc in the prefixed build.

Uses of BORINGSSL_MAKE_DELETER must be inside BSSL_NAMESPACE_BEGIN for
the specializations to work.

Change-Id: Ib96cf5d235586b24c052973d7034c0e5a8019f17
Reviewed-on: https://boringssl-review.googlesource.com/c/33346
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>

crypto/stack/stack_test.cc

diff --git a/crypto/stack/stack_test.cc b/crypto/stack/stack_test.cc
index 8b26971..7be84ed 100644
--- a/crypto/stack/stack_test.cc
+++ b/crypto/stack/stack_test.cc
@@ -31,9 +31,9 @@
 
 static void TEST_INT_free(TEST_INT *x) { OPENSSL_free(x); }
 
-namespace bssl {
+BSSL_NAMESPACE_BEGIN
 BORINGSSL_MAKE_DELETER(TEST_INT, TEST_INT_free)
-}  // namespace bssl
+BSSL_NAMESPACE_END
 
 static bssl::UniquePtr<TEST_INT> TEST_INT_new(int x) {
   bssl::UniquePtr<TEST_INT> ret(