Rename type variables in resolution of _cast [no objections]

Using dst and src as the names for the first and second argument of the cast
did not seem intuitive to me.  Did dst mean you were writing there, or did it
mean that was the type destination specified?  oldType and newType give a
clearer indication of what those sides mean.

tested on std/


git-svn-id: http://svn.code.sf.net/p/chapel/code/trunk@23587 3a8e244f-b0f2-452b-bcba-4c88e055c3ca
Fix bug in sub_test with setting a directory level timeout file and num-trials

[reviewed by elliot]

With the old behavior if a directory had a TIMEOUT file that was above
the default timeout we would still perform more than one trial. This is
undesirable for performance testing and will no longer happen.


git-svn-id: http://svn.code.sf.net/p/chapel/code/trunk@23588 3a8e244f-b0f2-452b-bcba-4c88e055c3ca