Rebase to FSF GDB 10.1.
Bump 'snapgnulib' date.
Drop gdb-rhbz1818011-bfd-gcc10-error.patch.
Drop gdb-rhbz1822715-fix-python-deprecation.patch.
Drop gdb-rhbz1829702-fix-python39.patch.
Drop gdb-rhbz1838777-debuginfod.patch.
Drop gdb-rhbz1844458-use-fputX_unfiltered.patch.
Drop gdb-rhbz1869484-deleted-working-directory.
Adjust build-id related patches.
Ajust VLA patches.