Fix old GCC ABI check in CMake package config (#72081)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/72081
This PR fixes the libstdc++ ABI check in CMake package configuration file (i.e. `TorchConfig.cmake`) The `_GLIBCXX_USE_CXX11_ABI` flag is a property of `libstdc++`, not GNU compiler collection. In its current form C++ libraries built with Clang on Linux fail since the `torch` CMake target propagates `_GLIBCXX_USE_CXX11_ABI` only when used with gcc.
ghstack-source-id: 148056323
Test Plan: Built a dummy C++ library that depends on libtorch with both gcc and clang on Linux
Reviewed By: malfet
Differential Revision: D33899849
fbshipit-source-id: 3e933b2c7a17d1fba086caa8aaec831223760882
(cherry picked from commit 41d18c64c4e88db615ecf6f3ef973bd8f985377a)
