Lock linker mutex in RelocateAnyImports (#3693)

Module relocation is not thread safe, games calling LoadAndStartModule on multiple threads can invalidate pointers while iterating through m_modules.

This fixes crashes in some apps on Windows.

src/core/linker.h

@@ -111,6 +111,8 @@ public:
     }
 
     void RelocateAnyImports(Module* m) {
+        std::scoped_lock lk{mutex};
+
         Relocate(m);
         const auto exports = m->GetExportModules();
         for (auto& export_mod : exports) {