Update to 0.78

Upstream changes:
Chnages for 0.78    Mon Apr 30 19:45:00 BST 2012
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* Use POSIX::_exit() instead of exit() in
  run_forked(). Reported by Mithun Ayachit
  [RT 76901]

Changes for 0.76    Mon Jan 30 11:30:53 GMT 2012
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* Make the empty arg stripping the default again,
  with option to override this behaviour.

Changes for 0.74    Mon Jan 30 10:24:30 GMT 2012
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* Applied patch from WATANABE Hiroaki [RT #74470]
  "Empty string cannot be passed to command"
* Resolved [RT #74373] reported by Randy Stauner
  "Compilation error when POSIX.pm fails to load"

(wen)