Remove the damage caused by my bad advice.

The old world never coped with > 32-bit file offsets, Mac OS doesn't have an
off64_t, and we should fix bionic to have _FILE_OFFSET_BITS rather than turd
up all calling code.

Change-Id: I0cb8b1f83fc19ce1fcf51257594551cfd1aa968c
diff --git a/src/file.h b/src/file.h
index babcb8b..3353602 100644
--- a/src/file.h
+++ b/src/file.h
@@ -27,11 +27,11 @@
 
   // Get the length of the file. Returns a negative value if the length cannot
   // be determined (e.g. not seekable device).
-  virtual off64_t Length() = 0;
+  virtual off_t Length() = 0;
 
   // Get the current position in the file.
   // Returns a negative value if position cannot be determined.
-  virtual off64_t Position() = 0;
+  virtual off_t Position() = 0;
 
   virtual int Fd() = 0;