Add *.pdf files to the clobber target (same target as *.ps).
diff --git a/Doc/Makefile b/Doc/Makefile
index d247101..9651db4 100644
--- a/Doc/Makefile
+++ b/Doc/Makefile
@@ -270,4 +270,4 @@
 
 # Remove temporaries as well as final products
 clobber: clean
-	 rm -f *.dvi *.ps *.texi *.info *.info-[0-9]*
+	 rm -f *.dvi *.pdf *.ps *.texi *.info *.info-[0-9]*