vm_core.h: sandwich jmpbuf
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59160 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
vm_core.h: sandwich jmpbuf
last in TH_PUSH_TAG, between tag and state so ensure to be
accessible. reapplied r40806.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59160 b2dd03c8-39d4-4d8f-98ff-823fe69b080e