Ignore and cleanup a few more files that automake creates.
diff --git a/config.h.in b/config.h.in
index a912bb0..e59a5a3 100644
--- a/config.h.in
+++ b/config.h.in
@@ -1,4 +1,4 @@
-/* config.h.in.  Generated from configure.in by autoheader.  */
+/* config.h.in.  Generated from configure.ac by autoheader.  */
 
 /* Define if .gnu.warning accepts long strings. */
 #undef HAS_GNU_WARNING_LONG