Clean up reserved identifier usage in src/ext include guards

src/ext/eventdns.h

@@ -209,8 +209,8 @@
  * with the next probe.
  */
 
-#ifndef _TOR_EVENTDNS_H
-#define _TOR_EVENTDNS_H
+#ifndef TOR_EVENTDNS_H
+#define TOR_EVENTDNS_H
 
 /* Error codes 0-5 are as described in RFC 1035. */
 #define DNS_ERR_NONE 0

src/ext/ht.h

@@ -5,8 +5,8 @@
 
 /* Based on ideas by Christopher Clark and interfaces from Niels Provos. */
 
-#ifndef _TOR_HT_H
-#define _TOR_HT_H
+#ifndef HT_H_INCLUDED_
+#define HT_H_INCLUDED_
 
 #define HT_HEAD(name, type)                                             \
   struct name {                                                         \