configure: move error message down to has_or_abort

When has_or_warn will come, we do want to print the error message
only in has_or_abort, so move it down there.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

 reporter_name="Remy Bohmer"

 reporter_url="linux@bohmer.net"

 reporter_comment="Example for building a toolchain for m68000 bare metal targets"