LibWeb: Show "x86_64" in the user agent string on x86_64 :^)

Userland/Libraries/LibWeb/Loader/ResourceLoader.h

@@ -17,7 +17,13 @@ class RequestClient;
 
 namespace Web {
 
-constexpr auto default_user_agent = "Mozilla/4.0 (SerenityOS; x86) LibWeb+LibJS (Not KHTML, nor Gecko) LibWeb";
+#if ARCH(I386)
+#    define CPU_STRING "x86"
+#else
+#    define CPU_STRING "x86_64"
+#endif
+
+constexpr auto default_user_agent = "Mozilla/4.0 (SerenityOS; " CPU_STRING ") LibWeb+LibJS (Not KHTML, nor Gecko) LibWeb";
 
 class ResourceLoader : public Core::Object {
     C_OBJECT(ResourceLoader)