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)
diff --git a/ssl/ssl_stat.c b/ssl/ssl_stat.c
index da8f5ed..3ef0e15 100644
--- a/ssl/ssl_stat.c
+++ b/ssl/ssl_stat.c
@@ -9,7 +9,7 @@
  */
 
 #include <stdio.h>
-#include "ssl_locl.h"
+#include "ssl_local.h"
 
 const char *SSL_state_string_long(const SSL *s)
 {