fake.rb: rubyarchhdrdir for rubyspec
* common.mk (test-rubyspec): use fake script to set header
directories.
* template/fake.rb.in (RUBYOPT): set -r option to propagate to
forked processes.
* tool/fake.rb (prehook): set rubyarchhdrdir too.
* too/fake.rb: don't fake libdir. use libdirname instead.
* tool/fake.rb: don't fake libdir. use libdirname instead.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_2@55637 b2dd03c8-39d4-4d8f-98ff-823fe69b080e