libc: make lseek64 proto be glibc compatible (loff_t -> off64_t)

Change-Id: Ib79b99be9ca8d4b1f95ceeba416b6abc04187c3c
Signed-off-by: Dima Zavin <dima@android.com>
diff --git a/libc/include/unistd.h b/libc/include/unistd.h
index 7554198..d90e737 100644
--- a/libc/include/unistd.h
+++ b/libc/include/unistd.h
@@ -131,7 +131,7 @@
 
 extern int close(int);
 extern off_t lseek(int, off_t, int);
-extern loff_t lseek64(int, loff_t, int);
+extern off64_t lseek64(int, off64_t, int);
 
 extern ssize_t read(int, void *, size_t);
 extern ssize_t write(int, const void *, size_t);