Remove files used for testing on macchapel-mac.

We are (finally) retiring this old mac system. Remove the scripts used for
testing (machine.macchapel-mac and preexec-for-old-macs) and remove the special
logic in smokeTest.
Merge pull request #561 from thomasvandoren/rm-macchapel-mac

Remove files used for testing on macchapel-mac.

We are retiring this old mac system. Remove the scripts used for
testing (machine.macchapel-mac and preexec-for-old-macs) and remove the special
logic in smokeTest.