gc.c: rb_gc_adjust_memory_usage
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@56189 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
gc.c: rb_gc_adjust_memory_usage
engine by extension libraries, to trigger GC. [Feature #12690]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@56189 b2dd03c8-39d4-4d8f-98ff-823fe69b080e