mpatch: use int rather than ssize_t
We might need to be more clever than this to make Py2.5 happy.
% init
% commit
adding base
% qnew mqbase
% qrefresh
% qdiff
diff -r 67e992f2c4f3 base
--- a/base
+++ b/base
@@ -1,1 +1,1 @@ base
-base
+patched
% qdiff dirname
diff -r 67e992f2c4f3 base
--- a/base
+++ b/base
@@ -1,1 +1,1 @@ base
-base
+patched