Fix C++ Ninja build on Windows

For Ninja builds we instruct the compiler to generate a dependency file.
This would include paths like builtin:/native/../common/slint-logo-light.svg,
which my version of Ninja on Windows doesn't like at all and just flat out aborts on.

It doesn't make sense for us to emit those as dependencies, so this patch excludes
builtin paths.

tools/compiler/main.rs

@@ -69,8 +69,12 @@ fn main() -> std::io::Result<()> {
             }
         }
         for resource in doc.root_component.embedded_file_resources.borrow().keys() {
+            if !fileaccess::load_file(&std::path::Path::new(resource))
+                .map_or(false, |f| f.is_builtin())
+            {
                 write!(f, " {}", resource)?;
             }
+        }
 
         writeln!(f)?;
     }