[Bug target/124001] wrong code generated with alignas() on armv8

[Joost.VandeVondele at mat dot ethz.ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124001

--- Comment #3 from Joost VandeVondele <Joost.VandeVondele at mat dot ethz.ch> ---
we will also look into reducing to a testcase

However, it is mentioned in the initial comment how to build, and takes about
15s:

make clean && make -j build ARCH=armv8 COMP=gcc COMPCXX=g++-15