/usr/lib/x86_64-linux-gnu/ is in libmagickwand-6.q16-dev 8:6.9.7.4+dfsg-16ubuntu6.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/x86_64-linux-gnu/ImageMagick-6.9.7/
/usr/lib/x86_64-linux-gnu/ImageMagick-6.9.7/bin-q16/
/usr/lib/x86_64-linux-gnu/ImageMagick-6.9.7/bin-q16/MagickWand-config
/usr/lib/x86_64-linux-gnu/ImageMagick-6.9.7/bin-q16/Wand-config
/usr/lib/x86_64-linux-gnu/libMagickWand-6.Q16.a
/usr/lib/x86_64-linux-gnu/libMagickWand-6.Q16.la
/usr/lib/x86_64-linux-gnu/pkgconfig/
/usr/lib/x86_64-linux-gnu/pkgconfig/MagickWand-im6.q16.pc
/usr/lib/x86_64-linux-gnu/libMagickWand-6.Q16.so
/usr/lib/x86_64-linux-gnu/pkgconfig/MagickWand-6.Q16.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/MagickWand-im6.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/MagickWand.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Wand-6.Q16.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Wand-im6.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Wand.pc