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_cert.c b/ssl/ssl_cert.c
index 185c12b..cb3a039 100644
--- a/ssl/ssl_cert.c
+++ b/ssl/ssl_cert.c
@@ -126,7 +126,7 @@
 
 #include "../crypto/dh/internal.h"
 #include "../crypto/directory.h"
-#include "ssl_locl.h"
+#include "internal.h"
 
 
 int SSL_get_ex_data_X509_STORE_CTX_idx(void) {