/usr/lib/x86_64-linux-gnu/ is in libgmpada3-dev 0.0.20110925-2.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/x86_64-linux-gnu/libgmpada.a
/usr/lib/x86_64-linux-gnu/ada/
/usr/lib/x86_64-linux-gnu/ada/adalib/
/usr/lib/x86_64-linux-gnu/ada/adalib/gmpada/
/usr/lib/x86_64-linux-gnu/ada/adalib/gmpada/gnu_multiple_precision-generic_text_io.ali
/usr/lib/x86_64-linux-gnu/ada/adalib/gmpada/gmp-binding.ali
/usr/lib/x86_64-linux-gnu/ada/adalib/gmpada/gnu_multiple_precision-wide_text_io.ali
/usr/lib/x86_64-linux-gnu/ada/adalib/gmpada/gnu_multiple_precision-text_io.ali
/usr/lib/x86_64-linux-gnu/ada/adalib/gmpada/gnu_multiple_precision.ali
/usr/lib/x86_64-linux-gnu/ada/adalib/gmpada/gmp-constants.ali
/usr/lib/x86_64-linux-gnu/ada/adalib/gmpada/gnu_multiple_precision-big_floats.ali
/usr/lib/x86_64-linux-gnu/ada/adalib/gmpada/gnu_multiple_precision-big_integers.ali
/usr/lib/x86_64-linux-gnu/ada/adalib/gmpada/gnu_multiple_precision-aux.ali
/usr/lib/x86_64-linux-gnu/ada/adalib/gmpada/gnu_multiple_precision-random_numbers.ali
/usr/lib/x86_64-linux-gnu/ada/adalib/gmpada/gnu_multiple_precision-wide_wide_text_io.ali
/usr/lib/x86_64-linux-gnu/ada/adalib/gmpada/gmp.ali
/usr/lib/x86_64-linux-gnu/ada/adalib/gmpada/gnu_multiple_precision-big_rationals.ali
/usr/lib/x86_64-linux-gnu/libgmpada.so