Prevent build errors due to mismatching target and triple

Set the target in accordance with the triple to avoid running into build
errors like `error: unknown target CPU 'x86-64'` when targeting e.g.
`aarch64-w64-mingw32`.

lib/cmake/modules/ReflectionGenerator.cmake

@@ -110,7 +110,7 @@ function (add_reflection_generator_invocation)
 
     # apply specified REFLECTION_GENERATOR_TRIPLET
     if (REFLECTION_GENERATOR_TRIPLE)
-        list(APPEND ARGS_CLANG_OPTIONS -Xclang -triple -Xclang "${REFLECTION_GENERATOR_TRIPLE}")
+        list(APPEND ARGS_CLANG_OPTIONS -target "${REFLECTION_GENERATOR_TRIPLE}" -Xclang -triple -Xclang "${REFLECTION_GENERATOR_TRIPLE}")
     endif ()
 
     # apply specified REFLECTION_GENERATOR_INCLUDE_DIRECTORIES