add a fileconfig entry to disable module culling

tests/projects/c++/modules/culling2/src/hello.mpp

@@ -0,0 +1,10 @@
+module;
+#include <cstdio>
+
+export module hello;
+
+export namespace hello {
+    void say(const char* str) {
+        printf("%s\n", str);
+    }
+}

tests/projects/c++/modules/culling2/test.lua

@@ -0,0 +1 @@
+inherit(".test_base")

tests/projects/c++/modules/culling2/xmake.lua

@@ -0,0 +1,6 @@
+add_rules("mode.release", "mode.debug")
+set_languages("c++20")
+
+target("culling")
+    set_kind("static")
+    add_files("src/*.mpp", {cull = true})

xmake/rules/c++/modules/modules_support/dependency_scanner.lua

@@ -427,7 +427,7 @@ function sort_modules_by_dependencies(target, objectfiles, modules)
                 local _, provide, cppfile = compiler_support.get_provided_module(modules[objectfile])
                 local fileconfig = target:fileconfig(cppfile)
                 local public = fileconfig and fileconfig.public
-                if not provide or public then
+                if not provide or public or (fileconfig.cull ~= nil and not fileconfig.cull) then
                     table.insert(result, objectfile)
                 end
             else