Make pybind11 not break builds that include cuda files.

dlib/external/pybind11/tools/pybind11Tools.cmake

@@ -198,6 +198,15 @@ function(pybind11_add_module target_name)
   if(MSVC)
     # /MP enables multithreaded builds (relevant when there are many files), /bigobj is
     # needed for bigger binding projects due to the limit to 64k addressable sections
-    target_compile_options(${target_name} PRIVATE /MP /bigobj)
+    set(msvc_extra_options /MP /bigobj)
+    if(CMAKE_VERSION VERSION_LESS 3.11)
+      target_compile_options(${target_name} PRIVATE ${msvc_extra_options})
+    else()
+      # Only set these options for C++ files.  This is important so that, for
+      # instance, projects that include other types of source files like CUDA
+      # .cu files don't get these options propagated to nvcc since that would
+      # cause the build to fail.
+      target_compile_options(${target_name} PRIVATE $<$<COMPILE_LANGUAGE:CXX>:${msvc_extra_options}>)
+    endif()
   endif()
 endfunction()