repo: use OSTREE_TIMESTAMP (=1) for checked-out files

1 is a better choice than 0 because some programs use 0
as a special value; for example, GNU Tar warns of an
"implausibly old timestamp" with 0.

Closes: #330
Approved by: cgwalters

src/libostree/ostree-repo-private.h

@@ -36,6 +36,8 @@ G_BEGIN_DECLS
 #define _OSTREE_SUMMARY_CACHE_DIR "summaries"
 #define _OSTREE_CACHE_DIR "cache"
 
+#define OSTREE_TIMESTAMP (1)
+
 typedef enum {
   OSTREE_REPO_TEST_ERROR_PRE_COMMIT = (1 << 0)
 } OstreeRepoTestErrorFlags;