R1:5bd526646144

Fix a PHP 8.1 deprecated use of strlen with a NULL argument

Summary:
This call prevents users to view a commit in subversion repositories
Indeed, if commiter and/or author field is not properly defined strlen is call with a NULL argument.
Using strlen to check string validity is deprecated since PHP 8.1, phorge adopts phutil_nonempty_string() as a replacement.

Note: this may highlight other absurd input values that might be worth correcting
instead of just ignoring. If phutil_nonempty_string() throws an…