Yes. Even Encyclopedia Britanicca defines Charavaka as an Indian Philosophy and not as an Hindu sect. [Charvaka]. All the scholars of Hinduism claim that those Indian traditions are Hindus. They want to absorb all the Indian tradition and call them under the term "Hindu". Now the sources which are being presented on Charvaka and Ajivika page to claim that they were Hindus are from mostly Hindu Scholars. Even Jains and Buddhists are not considered as a separate religion but thought of as an Hindu identity. In the Samaññaphala Sutta the philosophies existed at the time of Buddha are explained such as of the Ajivika Makkhali Gosala. Nigatha Nataputa (Mahavira) is also one of them. They disagreed with Buddha's dhamma so should we call them them Buddhists? But all the Hindu Scholars feel proud who even reject their scriptures(Vedas) to call them Hindus. Best regards.