merge revision(s) 51626: [Backport #11457]
* thread_pthread.c (reserve_stack): ensure the memory is really allocated. [Bug #11457]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_2@51985 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
merge revision(s) 51626: [Backport #11457]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_2@51985 b2dd03c8-39d4-4d8f-98ff-823fe69b080e