[PowerPC] Remove PRED_BAD from PPC::Predicate enumeration.

I'm taking David Blaikie's suggestion to use an
Optional<PPC::Predicate> return value instead.  That's the right
solution for this problem.  Thanks for pointing out that possibility!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183858 91177308-0d34-0410-b5e6-96231b3b80d8
Add global versions of some Program static methods.

This is a temporary stepping stone for moving them out of Program.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183860 91177308-0d34-0410-b5e6-96231b3b80d8
Revert r183854 (PPC: Fix switch warnings from r183841)

Now that the PRED_BAD has been removed, this is failing the Clang
-Werror build due to -Wcovered-switch-default.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183863 91177308-0d34-0410-b5e6-96231b3b80d8
Remove the program class.

It was only used to implement ExecuteAndWait and ExecuteNoWait. Expose just
those two functions and make Execute and Wait implementations details.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183864 91177308-0d34-0410-b5e6-96231b3b80d8