PPC: Use big-boy Types to annotate interface descriptor parameters

Port c019d7f4

Original commit message:
- Thread Type::FunctionType through stubs and the TF pipeline.
- Augment Typer to decorate parameter nodes with types from
  a Type::FunctionType associated with interface descriptors.
- Factor interface descriptors into platform-specific and
  platform-independent components so that all descriptors share
  a common Type::FunctionType for all platforms.

R=danno@chromium.org, dstence@us.ibm.com, michael_dawson@ca.ibm.com
BUG=

Review URL: https://codereview.chromium.org/1206893002

Cr-Commit-Position: refs/heads/master@{#29257}