XMonad.Util.Run: resolve issue #441
XMonad.Util.Run: resolve issue #441

Ignore-this: 9e3da81df65f6750c822a5044952f1a1
See <http://code.google.com/p/xmonad/issues/detail?id=441>

> I have run into programs that fail when run by safeSpawn but succeed with spawn.
> I tracked it down in one (python) and it seems to be due to uninstallSignalHandlers.
> When run by safeSpawn, the program reports errors from wait.

dylan did not supply a patch and his version doesn't match the declared type signature;
since I don't want to break every `safeSpawn` user, I tossed a `>> return ()` in to make
the type right, although I'm troubled at removing the exception functions.

darcs-hash:20110411163740-f7719-bf0d46f94d103cc328629ad32f8e650fec609cdc

kmels/xmonad-launcher,kmels/xmonad-launcher