include/ruby/internal/fl_type.h: refactor hoist out #if conditions
cf: https://github.com/ruby/ruby/pull/4100#pullrequestreview-575952836
include/ruby/internal/fl_type.h: refactor hoist out #if conditions
cf: https://github.com/ruby/ruby/pull/4100#pullrequestreview-575952836