Reorganize local header files

Apart from public and internal header files, there is a third type called
local header files, which are located next to source files in the source
directory. Currently, they have different suffixes like

  '*_lcl.h', '*_local.h', or '*_int.h'

This commit changes the different suffixes to '*_local.h' uniformly.

Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/9333)

test/tls13secretstest.c

diff --git a/test/tls13secretstest.c b/test/tls13secretstest.c
index 4756faa..def78b9 100644
--- a/test/tls13secretstest.c
+++ b/test/tls13secretstest.c
@@ -10,7 +10,7 @@
 #include <openssl/ssl.h>
 #include <openssl/evp.h>
 
-#include "../ssl/ssl_locl.h"
+#include "../ssl/ssl_local.h"
 #include "testutil.h"
 
 #define IVLEN   12