ADSP: Do not pass executable link flags when creating a static library

This was done by mistake in commit d090159318 (ENH: add support for the
ADSP toolchains for Blackfin, Shark and TigerShark DSPs, patch from
Raphael Cotty, 2007-07-12, v2.6.0~1446), and preserved in the
generalization by commit e9eabb0dcd (ADSP: Configure compiler in
compiler module, 2022-03-24, v3.24.0-rc1~331^2~1).  Fix both places.