Xext/xselinux: Warning fixes

There's a 'const char *' adventure here that I'm mostly ignoring; some
client information gets const poisoned. Worked around by adding a
couple of casts. Ick.

Added an _X_ATTRIBUTE_PRINTF to SELinuxLog.

Ignore a couple of unused return values.

Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Keith Packard <keithp@keithp.com>

Xext/xselinux_hooks.c

@@ -147,7 +147,7 @@ SELinuxLabelClient(ClientPtr client)
         strncpy(subj->command, cmdname, COMMAND_LEN - 1);
 
         if (!cached)
-            free(cmdname);     /* const char * */
+            free((void *) cmdname);     /* const char * */
     }
 
  finish:
@@ -294,6 +294,9 @@ SELinuxAudit(void *auditdata,
                     audit->extension ? audit->extension : "");
 }
 
+static int
+SELinuxLog(int type, const char *fmt, ...) _X_ATTRIBUTE_PRINTF(2, 3);
+
 static int
 SELinuxLog(int type, const char *fmt, ...)
 {
@@ -316,6 +319,7 @@ SELinuxLog(int type, const char *fmt, ...)
     va_start(ap, fmt);
     vsnprintf(buf, MAX_AUDIT_MESSAGE_LENGTH, fmt, ap);
     rc = audit_log_user_avc_message(audit_fd, aut, buf, NULL, NULL, NULL, 0);
+    (void) rc;
     va_end(ap);
     LogMessageVerb(X_WARNING, 0, "%s", buf);
     return 0;
@@ -476,7 +480,7 @@ SELinuxExtension(CallbackListPtr *pcbl, void *unused, void *calldata)
     }
 
     /* Perform the security check */
-    auditdata.extension = rec->ext->name;
+    auditdata.extension = (char *) rec->ext->name;
     rc = SELinuxDoCheck(subj, obj, SECCLASS_X_EXTENSION, rec->access_mode,
                         &auditdata);
     if (rc != Success)