/usr/lib/x86_64-linux-gnu/pkgconfig/ is in libgstreamer-plugins-base0.10-dev 0.10.36-1.1ubuntu2.1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/x86_64-linux-gnu/pkgconfig/gstreamer-fft-0.10.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/gstreamer-app-0.10.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/gstreamer-floatcast-0.10.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/gstreamer-rtsp-0.10.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/gstreamer-netbuffer-0.10.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/gstreamer-audio-0.10.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/gstreamer-tag-0.10.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/gstreamer-cdda-0.10.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/gstreamer-video-0.10.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/gstreamer-rtp-0.10.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/gstreamer-interfaces-0.10.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/gstreamer-sdp-0.10.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/gstreamer-plugins-base-0.10.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/gstreamer-riff-0.10.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/gstreamer-pbutils-0.10.pc