On svn-auth-x509 branch: avoid using svn_stringbuf_t/svn_string_t in
APIs that generate nul-terminated C strings.

* subversion/libsvn_subr/x509parse.c
  (fuzzy_escape, nul_escape, x509name_to_utf8_string): Change return type.
  (asn1_oid_to_string): Change parameter type.
  (x509_name_to_certinfo, x509parse_get_hostnames): Change variable type.

* subversion/libsvn_subr/x509info.c
  (deep_copy_array, deep_copy_hash): Add comments.


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/svn-auth-x509@1636393 13f79535-47bb-0310-9956-ffa450edef68