patch 9.0.1021: test trips over g:name

Problem:    Test trips over g:name.
Solution:   Delete g:name after using it.
diff --git a/src/testdir/runtest.vim b/src/testdir/runtest.vim
index ccd22e8..1d70a90 100644
--- a/src/testdir/runtest.vim
+++ b/src/testdir/runtest.vim
@@ -208,6 +208,7 @@
 for name in s:GetSwapFileList()
   call delete(name)
 endfor
+unlet name
 
 
 " Invoked when a test takes too much time.