configure: disable static linking on Darwin

Static liunking is not supported on Darwin, so hide the corresponding
options when the build machine is Darwin.

Reported-by: Andrea Franceschini <therealmorpheu5@gmail.com>
Reported-by: Bryan Hundven <bryanhundven@gmail.com>
Reported-by: "Titus von Boxberg" <titus@v9g.de>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

 reporter_name="Bart vdr. Meulen <bartvdrmeulen@gmail.com>"

 reporter_url=""

 reporter_comment="Config to build cross-compiler with mingw as kernel type"