Rename asn1_locl.h to internal.h.

Match the other internal headers.

Change-Id: I1b8e995b9a59fa02a7e38ee0ec9141e15655071a
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/48325
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/crypto/asn1/a_utctm.c b/crypto/asn1/a_utctm.c
index d5bd0e4..28f07ac 100644
--- a/crypto/asn1/a_utctm.c
+++ b/crypto/asn1/a_utctm.c
@@ -62,7 +62,7 @@
 #include <openssl/err.h>
 #include <openssl/mem.h>
 
-#include "asn1_locl.h"
+#include "internal.h"
 
 
 int asn1_utctime_to_tm(struct tm *tm, const ASN1_UTCTIME *d)