[Qemu-devel] Add infrastructure for supporting QIDL annotations

[Michael Roth]

These patches are based are origin/master, and can also be obtained from:

git://github.com/mdroth/qemu.git qidl-base

This is a cleanup of the infrastructure bits from
"[RFC v2] Use QEMU IDL for device serialization/introspection".

I know this is pretty late into the release cycle, but the patches in
this series have gotten decent review, and I have a seperate branch (qidl-conv1
in my github repo) that uses these bits to serialize i440fx, piix3/piix ide,
usb, cirrus_vga, and a few others via QIDL. So there shouldn't be too much
churn going forward.

Changes since rfc v2:

 - Parser/Codegen fix-ups for cases encountered converting piix ide and usb.
 - Fixed license headers.
 - Stricter arg-checking for QIDL macros when passing to codegen.
 - Added asserts to detect mis-use of QIDL property/visitor interfaces.
 - Renamed QAPI visit_*_array interfaces to visit_*_carray to clarify that
   these are serialization routines for single-dimension C arrays.