Add .dirstamp to toplevel .gitignore
diff --git a/.gitignore b/.gitignore
index f481dc4..8f39b53 100644
--- a/.gitignore
+++ b/.gitignore
@@ -39,5 +39,6 @@
 Makefile.in
 .dir-locals.el
 .deps/
+.dirstamp
 .libs/
 /Makefile