libstdc++: Fix order of changelog entries

Rebasing my last two commits put the changelog entries at the wrong
place in the file. Fixed by this change.

libstdc++-v3/ChangeLog

-2020-01-28  Martin Liska  <mliska@suse.cz>
-
-	PR libstdc++/93478
-	* include/std/atomic: Fix typo.
-	* include/std/optional: Likewise.
-
-2020-01-27  Andrew Burgess  <andrew.burgess@embecosm.com>
-
-	* configure: Regenerate.
-
 2020-01-28  Jonathan Wakely  <jwakely@redhat.com>
 
 	PR libstdc++/93470
@@ -19,6 +9,16 @@
 	clock_gettime instead of explicit glibc version check.
 	* configure: Regenerate.
 
+2020-01-28  Martin Liska  <mliska@suse.cz>
+
+	PR libstdc++/93478
+	* include/std/atomic: Fix typo.
+	* include/std/optional: Likewise.
+
+2020-01-27  Andrew Burgess  <andrew.burgess@embecosm.com>
+
+	* configure: Regenerate.
+
 2020-01-27  Jonathan Wakely  <jwakely@redhat.com>
 
 	PR libstdc++/93426