Merge branch 'maint'

* maint:
  filter-branch: Export variable `workdir' for --commit-filter
  Documentation/Makefile: add *.pdf to `clean' target
  Documentation: ignore *.pdf files

Documentation/.gitignore

@@ -3,6 +3,7 @@
 *.[1-8]
 *.made
 *.texi
+*.pdf
 git.info
 gitman.info
 howto-index.txt

Documentation/Makefile

@@ -232,6 +232,7 @@ cmd-list.made: cmd-list.perl ../command-list.txt $(MAN1_TXT)
 clean:
 	$(RM) *.xml *.xml+ *.html *.html+ *.1 *.5 *.7
 	$(RM) *.texi *.texi+ *.texi++ git.info gitman.info
+	$(RM) *.pdf
 	$(RM) howto-index.txt howto/*.html doc.dep
 	$(RM) technical/api-*.html technical/api-index.txt
 	$(RM) $(cmds_txt) *.made