typo: should be OPENSSL_free

Reviewed-by: Richard Levitte <levitte@openssl.org>

ssl/s3_lib.c

diff --git a/ssl/s3_lib.c b/ssl/s3_lib.c
index efd9683..8784642 100644
--- a/ssl/s3_lib.c
+++ b/ssl/s3_lib.c
@@ -2948,7 +2948,7 @@
     }
 
     if (s->s3->alpn_selected) {
-        free(s->s3->alpn_selected);
+        OPENSSL_free(s->s3->alpn_selected);
         s->s3->alpn_selected = NULL;
     }