Fold in/out/inout differentiation in to parser

This actually simplifies things a great deal, and means we don't need
buffer types back from the lexer for these three tokens. Small victories.

Change-Id: I5de6ef01852012ac60dd91238ba013662089ed0e
Test: unit tests
Bug: 24410295
Signed-off-by: Casey Dahlin <sadmac@google.com>
4 files changed