Add "const" to an "apr_array_header_t *" input parameter.
This is the only case in the whole API where it was missing.
(Note that we are allowed to add "const" to a pointer parameter of a public API, and have done so before e.g. in r922239, because that is a backward- compatible API change and doesn't change the ABI at all.)
* subversion/include/svn_repos.h subversion/libsvn_repos/repos.c (svn_repos_freeze): Add 'const' to the paths array parameter.