* thread_pthread.c (ruby_init_stack): Add STACK_GROW_DIR_DETECTION.
  This fixes a compilation failure while cross-compiling for ARM.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40476 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
add comments.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40477 b2dd03c8-39d4-4d8f-98ff-823fe69b080e