They're owned by the device instead of the swapchain.

Ignore SIGINT (in gdb_startup) so an interrupt from the command line
will break the debuggee and bring up the gdb prompt (instead of killing
both winedbg and the debuggee).

d3dcompiler_43: Don't use nameless unions in our private structures to avoid trouble with compilers where they are not supported.

This is also a first attempt at a more structured interface to blitter
operations.