Revert "Centralize the information about which object format we are using."

Revert "Centralize the information about which object format we are using."

This reverts commit r245047.

It was failing on the darwin bots. The problem was that when running

./bin/llc -march=msp430

llc gets to

  if (TheTriple.getTriple().empty())
    TheTriple.setTriple(sys::getDefaultTargetTriple());

Which means that we go with an arch of msp430 but a triple of
x86_64-apple-darwin14.4.0 which fails badly.

That code has to be updated to select a triple based on the value of
march, but that is not a trivial fix.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@245062 91177308-0d34-0410-b5e6-96231b3b80d8