Merge branch 'tc/last-modified'

A new command "git last-modified" has been added to show the closest
ancestor commit that touched each path.

* tc/last-modified:
  last-modified: use Bloom filters when available
  t/perf: add last-modified perf script
  last-modified: new subcommand to show when files were last modified

.gitignore

@@ -87,6 +87,7 @@
 /git-init-db
 /git-interpret-trailers
 /git-instaweb
+/git-last-modified
 /git-log
 /git-ls-files
 /git-ls-remote