Add generated release zip files to .gitignore.
diff --git a/.gitignore b/.gitignore
index 2bffdd0..ccd5f23 100644
--- a/.gitignore
+++ b/.gitignore
@@ -73,6 +73,7 @@
 doc/wiki/*.wiki
 
 libarchive-*.tar.gz
+libarchive-*.zip
 
 Testing/
 libarchive/libarchive.a