Search parent directories for default*.do.

Previously, we would only search for default*.do in the same directory in
the target; now we search parent directories as well.

Let's say we're in a/b/ and trying to build foo.o.  If we find
../../default.o.do, then we'll run

	cd ../..; sh default.o.do a/b/foo .o $TMPNAME

In other words, we still always chdir to the same directory as the .do file.
But now $1 might have a path in it, not just a basename.

state.py

@@ -261,7 +261,7 @@ class File(object):
 
     def add_dep(self, mode, dep):
         src = File(name=dep)
-        debug2('add-dep: %r < %s %r\n' % (self.name, mode, src.name))
+        debug3('add-dep: "%s" < %s "%s"\n' % (self.name, mode, src.name))
         assert(self.id != src.id)
         _write("insert or replace into Deps "
                "    (target, mode, source, delete_me) values (?,?,?,?)",