Update abicheck to require newer libstdc++.so.6

We should update projects/firefox/abicheck.cc to use features only provided by more recent versions of libstdc++.so.6.

Currently it only requires GLIBCXX_3.4.22:

$ strings tor-browser_en-US/Browser/abicheck | grep GLIBCXX_
GLIBCXX_3.4
GLIBCXX_3.4.22
GLIBCXX_3.4.21

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