In uh... South Africa?
No, it didn't mean "black people" in its original form. It meant "black non-Muslims" as the Portuguese used it. And that by the way is from your own link.
And from a sub-link off that link:
>>
Kafir (
Arabic: كافر
kāfir; plural كفّار
kuffār; feminine كافرة
kāfirah) is an Arabic term (from the root K-F-R "to cover") used in an Islamic doctrinal sense, usually translated as "unbeliever," "disbeliever," or "
infidel". The term
[4] alludes to a person who rejects or disbelieves in God and the religious truth revealed through the mission of the
Islamic Prophet
Muhammad, and thus demonstrates ingratitude towards God;
[5] denies, refuses to accept the dominion and authority of God;
[6] or otherwise does not heed the beliefs and prescriptions held by the religion of Islam. Unbelief is called
kufr.
Kafir is sometimes used interchangeably with
mushrik (مشرك, those who commit polytheism), another type of religious wrongdoer mentioned frequently in the Quran and Islamic works.
[7] Jews and Christians are regarded as kuffar.
[5][7] The practise of declaring another self-professed Muslim a kafir is known as
takfir.
[8] <<
Ruh-roh. Nothing about "black" or any other colour in there.
I've got Kaffir lime leaves in my cupboard. Looking for a good recipe to use 'em.