/usr/src/gcc-4.8/debian/libx32atomic1.symbols is in gcc-4.8-source 4.8.2-19ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 | libatomic.so.1 libx32atomic1 #MINVER#
#include "libatomic1.symbols.common"
#include "libatomic1.symbols.64"
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