Add mutex for `lb_handle_objc_find_or_register_selector`

src/llvm_backend.hpp

@@ -165,6 +165,7 @@ struct lbModule {
 	PtrMap<u64/*type hash*/, LLVMTypeRef>  func_raw_types;         // mutex: func_raw_types_mutex
 	RecursiveMutex types_mutex;
 	RecursiveMutex func_raw_types_mutex;
+	RecursiveMutex objc_selectors_mutex;
 	i32 internal_type_level;
 
 	RwMutex values_mutex;

src/llvm_backend_utility.cpp

@@ -2096,7 +2096,11 @@ gb_internal void lb_set_wasm_export_attributes(LLVMValueRef value, String export
 
 
 gb_internal lbAddr lb_handle_objc_find_or_register_selector(lbProcedure *p, String const &name) {
+	mutex_lock(&p->module->objc_selectors_mutex);
+	defer (mutex_unlock(&p->module->objc_selectors_mutex));
+
 	lbObjcRef *found = string_map_get(&p->module->objc_selectors, name);
+
 	if (found) {
 		return found->local_module_addr;
 	}
@@ -2118,7 +2122,10 @@ gb_internal lbAddr lb_handle_objc_find_or_register_selector(lbProcedure *p, Stri
 		lbAddr default_addr = lb_add_global_generated_with_name(default_module, t_objc_SEL, {},
 			make_string(cast(u8 const *)global_name, gb_string_length(global_name)),
 			&entity);
+
+		mutex_lock(&default_module->objc_selectors_mutex);
 		string_map_set(&default_module->objc_selectors, name, lbObjcRef{entity, default_addr});
+		mutex_unlock(&default_module->objc_selectors_mutex);
 	}
 
 	lbValue ptr = lb_find_value_from_entity(p->module, entity);