Fix overzealous .hgignore file
diff --git a/.hgignore b/.hgignore
index 8056e98..021fef1 100644
--- a/.hgignore
+++ b/.hgignore
@@ -1,8 +1,8 @@
 .gdb_history
 .purify
 .svn
-Makefile
-Makefile.pre
+Makefile$
+Makefile.pre$
 TAGS
 autom4te.cache
 build