Currently there is `NtContinue()` test only for `aarch64` so implement it for amd64 aswell.
This implementation is very similar to `aarch64` and it's very basic test.
It doesn't change/test `ContextFlags` so it won't catch https://bugs.winehq.org/show_bug.cgi?id=56050 but that can be implemented later on top of this.
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v6: ntdll/tests: Implement test_continue() for amd64
https://gitlab.winehq.org/wine/wine/-/merge_requests/4720
Conflicts with !450 but can probably go upstream before it since backend changes here are minimal.
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v7: vkd3d-shader/dxil: Handle the DXIL SWITCH instruction.
vkd3d-shader: Rename shader_instruction_array_add_icb() to shader_instruction_array_add_opaque_param().
vkd3d-shader/dxil: Handle the DXIL PHI instruction.
vkd3d-shader/dxil: Handle the DXIL BR instruction conditional variant.
vkd3d-shader/dxil: Handle the DXIL BR instruction unconditional variant.
https://gitlab.winehq.org/wine/vkd3d/-/merge_requests/491