ddraw_layout: pins the guest DirectDraw/D3D7 structs in
src/runtime/hle/ddraw_types.h to the real 32-bit SDK layout.

fields.inc lists every struct/field of ddraw_types.h (regenerate it with
the small Python snippet in the git history if the structs change, or edit
by hand: S(T) for sizes, F(T, our_field, sdk_field) for offsets).

Regenerate the checks (dev-time; uses mingw-w64 headers and wine):

  i686-w64-mingw32-gcc -O0 -o /tmp/ddraw_layout.exe ddraw_layout.c
  wine /tmp/ddraw_layout.exe > ../../src/runtime/hle/ddraw_layout_check.inc

The output is a list of static_asserts compiled into the runtime, so any
mismatch is a build error.

d3d9_layout.c / d3d9_fields.inc do the same for d3d9_types.h:

  i686-w64-mingw32-gcc -O0 -o /tmp/d3d9_layout.exe d3d9_layout.c
  wine /tmp/d3d9_layout.exe > ../../src/runtime/hle/d3d9_layout_check.inc

(d3d9_fields.inc lists every struct/field of d3d9_types.h; LARGE_INTEGER
DriverVersion is split into DriverVersionLowPart/HighPart.)
