Makes SCT_get0_log return const CTLOG*

Reviewed-by: NEmilia Käsper <emilia@openssl.org>
Reviewed-by: NRich Salz <rsalz@openssl.org>

crypto/ct/ct_locl.h

@@ -126,7 +126,7 @@ struct sct_st {
     /* Where this SCT was found, e.g. certificate, OCSP response, etc. */
     sct_source_t source;
     /* The CT log that produced this SCT. */
-    CTLOG *log;
+    const CTLOG *log;
     /* The result of the last attempt to validate this SCT. */
     sct_validation_status_t validation_status;
 };

crypto/ct/ct_sct.c

@@ -339,7 +339,7 @@ int SCT_LIST_set_source(const STACK_OF(SCT) *scts, sct_source_t source)
     return ret;
 }
 
-CTLOG *SCT_get0_log(const SCT *sct)
+const CTLOG *SCT_get0_log(const SCT *sct)
 {
     return sct->log;
 }

include/openssl/ct.h

@@ -315,7 +315,7 @@ __owur int SCT_LIST_set_source(const STACK_OF(SCT) *scts, sct_source_t source);
 /*
  * Gets information about the log the SCT came from, if set.
  */
-CTLOG *SCT_get0_log(const SCT *sct);
+const CTLOG *SCT_get0_log(const SCT *sct);
 
 /*
  * Looks up information about the log the SCT came from using a CT log store.