/usr/share/dpkg/pie-link.specs is in libdpkg-perl 1.19.0.5ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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*self_spec: + %{!static:%{!shared:%{!r:%{!fno-PIE:%{!no-pie:-fPIE -pie}}}}}