fix: conflicting packages when using -I

Originally fixed in b7893a2c, that approach created another bug when packages have several providers. In that case, pacman expects a number, so "yes" is not a valid answer, leading to an infinite loop.

Using the undocumented, but stable option "--ask=4" allows to selectively change the default answer for conflicts, therefore properly fixing the underlying issue. See also: pacman/pacman#60

Fixes #163 (closed)

Component: makechrootpkg