New GC library was released.
I use git subtree command to import new GC library from https://github.com/ivmai/bdwgc and https://github.com/ivmai/libatomic_ops .
Many local patches are dropped. Because I don't know what to do about those patches.
Prepare to update "bdwgc" 7.4.4 and "libatomic_ops" 7.4.4
Squashed 'gc/' content from commit d8bfa89
Merge commit '19389a4bd94eb8a56cce5b6af9c8b8bd700f8fa7' as 'gc'
Squashed 'gc/libatomic_ops/' content from commit 3a497aa
Merge commit '210b52884de134da39ef153d179bfa2d59c144f4' as 'gc/libato…
Install required files from "autgen.sh" script in "gc/"
Back-port sigmask hack from "bdwgc" 7.5.0
Gauche's GC sigmask hack is now merged into upstream.
This is the back-port patch from current master branch, "bdwgc" 7.5.0.
give me a few more days to assess the effects.