Merged from r221056:

Merged from r221056:

[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.

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/branches/release_35@223034 91177308-0d34-0410-b5e6-96231b3b80d8