Sink DwarfUnit::Skeleton down into DwarfCompileUnit

Type units no longer have skeletons and it's misleading to be able to
query for a type unit's skeleton (it might incorrectly lead one to
conclude that if a unit doesn't have a skeleton it's not in a .dwo
file... ).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221055 91177308-0d34-0410-b5e6-96231b3b80d8
[mips] Move F128 argument handling into MipsCCState as we did for returns. NFC.

Summary:
There are a couple more changes to make before analyzeFormalArguments can
be merged into the standard AnalyzeFormalArguments. I've had to temporarily
poke a couple holes in MipsCCState's encapsulation to save having to make
all the required changes for this merge all at once*. These will be removed
shortly.

* We must merge our ByVal argument handling with the implementation in CCState.
  This will be done over the next three patches, then the fourth will merge
  analyzeFormalArguments with AnalyzeFormalArguments.

Depends on D5967

Reviewers: vmedic

Reviewed By: vmedic

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D5969

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221056 91177308-0d34-0410-b5e6-96231b3b80d8
[mips] Remove ByValArgInfo::Address in favour of CCValAssign::getMemLocOffset(). NFC.

Summary: ByValArgInfo is practically the same as CCState::ByValInfo now.

Reviewers: vmedic

Reviewed By: vmedic

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D5976

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221057 91177308-0d34-0410-b5e6-96231b3b80d8
[mips] Fix unused variable warning introduced in r221056


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221058 91177308-0d34-0410-b5e6-96231b3b80d8