rec_x64: Avoid recipe for target failed error

core/emitter/x86_emitter.h

@@ -229,6 +229,7 @@ struct /*__declspec(dllexport)*/  x86_ptr_imm
 		this->ptr=ptr;
 	}
 
+#if HOST_CPU != CPU_X64
 #ifndef WIN32
 	template<typename Rv, typename ...Args>
 	x86_ptr_imm(Rv(* ptr)(Args...))
@@ -242,6 +243,7 @@ struct /*__declspec(dllexport)*/  x86_ptr_imm
     {
         this->ptr= reinterpret_cast<void*>(ptr);
     }
+#endif
 };
 
 enum x86_mrm_mod