Use OPENSSL_free instead of free.

Even if OPENSSL_free() now simply is defined to free(), it is
still nice to consistently use OPENSSL_free, so that they can
easily be replaced. Many embedded platforms still have slow
allocation and free functions.

Change-Id: Ie8781591311f12c7f69206dbad6fc4a0c89d88b7
Reviewed-on: https://boringssl-review.googlesource.com/1490
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/ssl/s3_lib.c b/ssl/s3_lib.c
index e31552a..2efb58e 100644
--- a/ssl/s3_lib.c
+++ b/ssl/s3_lib.c
@@ -2207,7 +2207,7 @@
 
 	if (s->s3->alpn_selected)
 		{
-		free(s->s3->alpn_selected);
+		OPENSSL_free(s->s3->alpn_selected);
 		s->s3->alpn_selected = NULL;
 		}
 	memset(s->s3,0,sizeof *s->s3);