Fix ASan bot.

This restores the original semantics of the finished hook.

Change-Id: I70da393c7e66fb6e3be1e2511e08b34bb54fc0b4
Reviewed-on: https://boringssl-review.googlesource.com/6422
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/crypto/rsa/rsa.c b/crypto/rsa/rsa.c
index 482a866..2589c14 100644
--- a/crypto/rsa/rsa.c
+++ b/crypto/rsa/rsa.c
@@ -138,7 +138,9 @@
     return;
   }
 
-  if (rsa->meth->finish) {
+  if (rsa->meth == &RSA_default_method) {
+    rsa_default_finish(rsa);
+  } else if (rsa->meth->finish) {
     rsa->meth->finish(rsa);
   }
   METHOD_unref(rsa->meth);