libenca: new package

Extremely Naive Charset Analyser.

This package was originally found at : https://github.com/huceke/buildroot-rbp


By gimli <ebsi4711@gmail.com>

[Peter: drop libiconv dep, tools patch, simplify host tools build]
Signed-off-by: Maxime Hadjinlian <maxime.hadjinlian@gmail.com>
Cc: gimli <ebsi4711@gmail.com>
Cc: Bernd Kuhls <berndkuhls@hotmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>