libhardware_headers: vendor modules on host

The build has us build headers in different ways for vendor or
host. Maybe we should change them to be more symmetrical. Anyway,
this works!

Fixes: 403014159
Test: add 'consumerir.default' as host supported and build it
  (it gets past the includes, but it fails for other reasons)
Change-Id: Ic86d61c43bb82dff0bbe8f21ec85fdac4db4fe2d