Change update-submodules.pl to not use the shell at all
Change update-submodules.pl to not use the shell at all

This should make this more platform agnostic and a bit safer.
As a side effect of this the detailed error reporting that checked the
STDERR and reported based on that is now gone, because it's not easily
possible in perl to capture STDERR without using backticks.

nbrown/rakudo,salortiz/rakudo,labster/rakudo,softmoth/rakudo,softmoth/rakudo,tbrowder/rakudo,rakudo/rakudo,MasterDuke17/rakudo,nbrown/rakudo,MasterDuke17/rakudo,rakudo/rakudo,MasterDuke17/rakudo,salortiz/rakudo,tony-o/rakudo,salortiz/rakudo,nbrown/rakudo,tony-o/rakudo,labster/rakudo,MasterDuke17/rakudo,rakudo/rakudo,salortiz/rakudo,nbrown/rakudo,tbrowder/rakudo,softmoth/rakudo,labster/rakudo,rakudo/rakudo,labster/rakudo,rakudo/rakudo,MasterDuke17/rakudo,MasterDuke17/rakudo,softmoth/rakudo,tbrowder/rakudo,salortiz/rakudo,softmoth/rakudo,labster/rakudo,tbrowder/rakudo,nbrown/rakudo,salortiz/rakudo,labster/rakudo,tbrowder/rakudo,tony-o/rakudo,tony-o/rakudo,tony-o/rakudo,rakudo/rakudo,tony-o/rakudo,tbrowder/rakudo,nbrown/rakudo