Avoid setting unused variables (-Wself-assign)

Setting a variable and then assigning it to itself avoids
-Wunused-but-set-variable but this specific trick is now caught by
-Wself-assign. Instead, actually use the value or don't bother
assigning it at all:

gdbusauthmechanismsha1.c: #ifdef a var decl to match its actual use use
gdbusauthmechanismsha1.c: call g_ascii_strtoll() in void context

https://bugzilla.gnome.org/show_bug.cgi?id=745723

gio/gdbusauthmechanismsha1.c

@@ -389,7 +389,6 @@ keyring_lookup_entry (const gchar  *cookie_context,
       gchar **tokens;
       gchar *endp;
       gint line_id;
-      guint64 line_when;
 
       if (line[0] == '\0')
         continue;
@@ -422,8 +421,7 @@ keyring_lookup_entry (const gchar  *cookie_context,
           goto out;
         }
 
-      line_when = g_ascii_strtoll (tokens[1], &endp, 10);
-      line_when = line_when; /* To avoid -Wunused-but-set-variable */
+      (void)g_ascii_strtoll (tokens[1], &endp, 10); /* do not care what the timestamp is */
       if (*endp != '\0')
         {
           g_set_error (error,
@@ -490,7 +488,9 @@ keyring_acquire_lock (const gchar  *path,
   gchar *lock;
   gint ret;
   guint num_tries;
+#ifdef EEXISTS
   guint num_create_tries;
+#endif
   int errsv;
 
   g_return_val_if_fail (path != NULL, FALSE);
@@ -512,8 +512,8 @@ keyring_acquire_lock (const gchar  *path,
    *         real locking implementations are still flaky on network filesystems
    */
 
-  num_create_tries = 0;
 #ifdef EEXISTS
+  num_create_tries = 0;
  again:
 #endif
   num_tries = 0;
@@ -562,7 +562,6 @@ keyring_acquire_lock (const gchar  *path,
             goto again;
         }
 #endif
-      num_create_tries = num_create_tries; /* To avoid -Wunused-but-set-variable */
       g_set_error (error,
                    G_IO_ERROR,
                    g_io_error_from_errno (errsv),