[guix] bump glibc to 2.8
Summary:
For future reference, this is how the hash is computed:
git clone https://sourceware.org/git/glibc.git cd glibc/ git checkout c9e58ae23402eb82877de90fd8a18519c086ed87 guix hash --exclude-vcs --serializer=nar .
Test Plan:
contrib/guix/guix-clean contrib/guix/guix-build
Reviewers: #bitcoin_abc, Fabien
Reviewed By: #bitcoin_abc, Fabien
Differential Revision: https://reviews.bitcoinabc.org/D13979