android: prepare simplified utf support

disable utf-8 config, not compatible with bionic

mb functions, and even simple strnlen is not compatible
manual checks should be added to prevent cursor inside
extended unicode characters.

vim implementation is correct, but not this one which
depends on ncursesw or slang

Signed-off-by: Tanguy Pruvot <tanguy.pruvot@gmail.com>

Change-Id: I5fea58bd00731ae2262763dce3ef2f0b054bbe1a
set tabs to 4

Change-Id: I9eff3e451143a744d5ddc466bacc19e29ffb0e57
fix some type warnings

Change-Id: Ifb153429f8129e4da35d7e3c3186e674e7330f8d
warnings

Change-Id: Iab7260592f52a85e6e93f3dbdac6a6e264487cda