/usr/lib/x86_64-linux-gnu/ is in libgstreamermm-1.0-dev 1.10.0+dfsg-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/x86_64-linux-gnu/gstreamermm-1.0/
/usr/lib/x86_64-linux-gnu/gstreamermm-1.0/gen/
/usr/lib/x86_64-linux-gnu/gstreamermm-1.0/gen/generate_plugin_gmmproc_file
/usr/lib/x86_64-linux-gnu/gstreamermm-1.0/gen/m4/
/usr/lib/x86_64-linux-gnu/gstreamermm-1.0/gen/m4/class_boxedtype_extra.m4
/usr/lib/x86_64-linux-gnu/gstreamermm-1.0/gen/m4/convert.m4
/usr/lib/x86_64-linux-gnu/gstreamermm-1.0/gen/m4/convert_gst.m4
/usr/lib/x86_64-linux-gnu/gstreamermm-1.0/gen/m4/plugingen.m4
/usr/lib/x86_64-linux-gnu/gstreamermm-1.0/gen/m4/plugingen_base.m4
/usr/lib/x86_64-linux-gnu/gstreamermm-1.0/gen/m4/plugingen_gstreamermm.m4
/usr/lib/x86_64-linux-gnu/gstreamermm-1.0/gen/m4/shared.m4
/usr/lib/x86_64-linux-gnu/gstreamermm-1.0/include/
/usr/lib/x86_64-linux-gnu/gstreamermm-1.0/include/gstreamermmconfig.h
/usr/lib/x86_64-linux-gnu/pkgconfig/
/usr/lib/x86_64-linux-gnu/pkgconfig/gstreamermm-1.0.pc
/usr/lib/x86_64-linux-gnu/libgstreamermm-1.0.so