Changing instances of $? to $status

[trivial, not reviewed]

Jun Nakashima points out that the use of $? is tcsh-specific and
will only work on machines for which csh is an alias for tcsh.
Changing to $status for portability's sake.



git-svn-id: http://svn.code.sf.net/p/chapel/code/trunk@22129 3a8e244f-b0f2-452b-bcba-4c88e055c3ca