Remove the OSTREE_MAX_RECURSION limit on metadata depth

This was making it impossible to pull or mirror a large ostree repo, and
according to Colin is no longer necessary. It works fine with a test
against a repo with 2741 commit and 451468 objects in it.

Closes: #899

Closes: #904
Approved by: jlebon

src/libostree/ostree-core.h

@@ -44,13 +44,6 @@ G_BEGIN_DECLS
  */
 #define OSTREE_MAX_METADATA_WARN_SIZE (7 * 1024 * 1024)
 
-/**
- * OSTREE_MAX_RECURSION:
- * 
- * Maximum depth of metadata.
- */
-#define OSTREE_MAX_RECURSION (256)
-
 /**
  * OSTREE_SHA256_DIGEST_LEN:
  *