libobs-d3d11: Use OS D3DCompiler_47.dll in legacy CMake

Follow-up to 972e24df796f6d57a4e63c101e7ae17121a54c11.

libobs-d3d11/cmake/legacy.cmake

@@ -39,7 +39,7 @@ else()
   target_compile_definitions(libobs-d3d11 PRIVATE USE_GPU_PRIORITY=TRUE GPU_PRIORITY_VAL=${GPU_PRIORITY_VAL})
 endif()
 
-target_link_libraries(libobs-d3d11 PRIVATE OBS::libobs d3d9 d3d11 dxgi shcore)
+target_link_libraries(libobs-d3d11 PRIVATE OBS::libobs d3d9 d3d11 d3dcompiler dxgi shcore)
 
 set_target_properties(
   libobs-d3d11