/usr/lib/pd-gui/plugins-available/ is in pd-iemutils 0.0.20180206-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/pd-gui/plugins-available/patcherize-plugin/
/usr/lib/pd-gui/plugins-available/patcherize-plugin/Makefile.pdlibbuilder
/usr/lib/pd-gui/plugins-available/patcherize-plugin/patcherize-help.pd
/usr/lib/pd-gui/plugins-available/patcherize-plugin/patcherize-plugin.tcl
/usr/lib/pd-gui/plugins-available/patcherize-plugin/patcherize.pd_linux
/usr/lib/pd-gui/plugins-available/triggerize-plugin/
/usr/lib/pd-gui/plugins-available/triggerize-plugin/Makefile.pdlibbuilder
/usr/lib/pd-gui/plugins-available/triggerize-plugin/triggerize-help.pd
/usr/lib/pd-gui/plugins-available/triggerize-plugin/triggerize-plugin.tcl
/usr/lib/pd-gui/plugins-available/triggerize-plugin/triggerize.pd_linux