plugins: fix cross-build using LLVM for Windows targets

plugins: fix cross-build using LLVM for Windows targets

llvm-dlltool assumes that it's by default targeting the host architecture
it's running on. That assumption doesn't hold true when cross-compiling.

Signed-off-by: Mohamed Mediouni <mohamed@unpredictable.fr>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Tested-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Link: https://lore.kernel.org/qemu-devel/20260210040722.11375-1-mohamed@unpredictable.fr
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>