Rename ssl_locl.h to internal.h

Match the other internal headers.

Change-Id: Iff7e2dd06a1a7bf993053d0464cc15638ace3aaa
Reviewed-on: https://boringssl-review.googlesource.com/4280
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/ssl/ssl_stat.c b/ssl/ssl_stat.c
index 4703af4..8bed9ad 100644
--- a/ssl/ssl_stat.c
+++ b/ssl/ssl_stat.c
@@ -83,7 +83,7 @@
  */
 
 #include <stdio.h>
-#include "ssl_locl.h"
+#include "internal.h"
 
 const char *SSL_state_string_long(const SSL *s) {
   const char *str;