gdb-add-index now removes its temp directory

This fixes a bug in gdb-add-index that meant it never cleaned up its
temp files.

Review-Url: https://codereview.chromium.org/2023363002
Cr-Commit-Position: refs/heads/master@{#397226}
diff --git a/build/gdb-add-index b/build/gdb-add-index
index 8df437f7..73367c83 100755
--- a/build/gdb-add-index
+++ b/build/gdb-add-index
@@ -36,7 +36,7 @@
     echo "done"
   fi
 
-  if [ -f "$directory" ]; then
+  if [ -d "$directory" ]; then
     echo -n "Removing temp directory $directory..."
     rm -rf "$directory"
     echo done