/usr/src/gcc-4.8/debian/lib32itm1.symbols is in gcc-4.8-source 4.8.5-4ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 | libitm.so.1 lib32itm1 #MINVER#
#include "libitm1.symbols.common"
#include "libitm1.symbols.32bit"
(arch=amd64 i386 x32)#include "libitm1.symbols.x86"
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