Deprecate Low Level Blowfish APIs

Applications should instead use the higher level EVP APIs, e.g.
EVP_Encrypt*() and EVP_Decrypt*().

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/10740)
diff --git a/test/bftest.c b/test/bftest.c
index 5b48925..f350ce7 100644
--- a/test/bftest.c
+++ b/test/bftest.c
@@ -8,9 +8,10 @@
  */
 
 /*
- * This has been a quickly hacked 'ideatest.c'.  When I add tests for other
- * RC2 modes, more of the code will be uncommented.
+ * BF low level APIs are deprecated for public use, but still ok for internal
+ * use.
  */
+#include "internal/deprecated.h"
 
 #include <stdio.h>
 #include <string.h>