Actually use a target specific compiler

Unless a compiler which produces code for the target is setup, the
result of the compilation (if successful) will just be native code which
isn't helpful. Setup target specific gcc && linker instead

Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Reviewed-by: Guillaume Desmottes <guillaume.desmottes@collabora.co.uk>
Differential Revision: https://phabricator.apertis.org/D5257