print/qpdf: Update to 7.1.1 (a followup release)

Fixed bugs that were left by the first commit for bug#225226
that updated qpdf to 7.1.0:

• build breaks when previous version is installed: https://github.com/qpdf/qpdf/issues/176
• error: reinterpret_cast from 'nullptr_t' to 'char *': https://github.com/qpdf/qpdf/issues/177

PR: 225226
Reported by: several users
Approved by: adamw (mentor)
Differential Revision: https://reviews.freebsd.org/D14201