[mips] Move all ByVal handling into CCState and tablegen-erated code. NFC.

Summary:
CCState already contains a byval implementation that is very similar to the
Mips custom code. This patch merges the custom code into the existing
common code and tablegen-erated code.

Reviewers: vmedic

Reviewed By: vmedic

Subscribers: rnk, llvm-commits

Differential Revision: http://reviews.llvm.org/D5977

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221059 91177308-0d34-0410-b5e6-96231b3b80d8
Make DwarfCompileUnit::Skeleton more narrowly typed (DwarfCompileUnit* instead of DwarfUnit*) now that it's specific to DwarfCompileUnit anyway.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221060 91177308-0d34-0410-b5e6-96231b3b80d8
Renamed CCState members that appear to misspell 'Processed' as 'Proceed'. NFC.

Reviewers: rnk

Reviewed By: rnk

Subscribers: rnk, llvm-commits

Differential Revision: http://reviews.llvm.org/D5978

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221061 91177308-0d34-0410-b5e6-96231b3b80d8
Sink DwarfUnit::SectionSym into DwarfCompileUnit as it's only needed/used there.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221062 91177308-0d34-0410-b5e6-96231b3b80d8