/usr/src/gcc-4.8/debian/libgnat-BV.overrides is in gcc-4.8-source 4.8.4-2ubuntu1~14.04.4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1
libgnat-@BV@ binary: package-name-doesnt-match-sonames