/usr/src/gcc-8/debian/libatomic.symbols is in gcc-8-source 8-20180414-1ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 | libatomic.so.1 #PACKAGE# #MINVER#
(symver)LIBATOMIC_1.0 4.8
(symver)LIBATOMIC_1.1 4.9
(symver)LIBATOMIC_1.2 6
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