Cosmetic change only: Fix spacing and indentation.

* subversion/libsvn_subr/io.c

  (svn_io_create_custom_diff_cmd): Fix indentation and spacing.


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/invoke-diff-cmd-feature@1525836 13f79535-47bb-0310-9956-ffa450edef68