Fix linking of the interpreter

I don't know why, byt the 'crate-type = "lib"' seem to fix the problem

api/sixtyfps-cpp/Cargo.toml

@@ -11,7 +11,7 @@ publish = false
 
 [lib]
 path = "lib.rs"
-crate-type = ["cdylib"]
+crate-type = ["lib", "cdylib"]
 
 [features]
 # In the future, this shouldn't be a default feature, but should be enabled by cmake

api/sixtyfps-cpp/lib.rs

@@ -11,7 +11,7 @@ LICENSE END */
 
 #[doc(hidden)]
 #[cold]
-pub extern "C" fn use_modules() -> usize {
+pub fn use_modules() -> usize {
     #[cfg(feature = "sixtyfps-interpreter")]
     sixtyfps_interpreter::use_modules();
     sixtyfps_rendering_backend_default::use_modules();