s390x: Update math: redirect roundeven function

After recent commit
447954a2
"math: redirect roundeven function", building on
s390x fails with:
Error: symbol `__roundevenl' is already defined

Similar to aarch64/riscv fix, this patch redirects target
specific functions for s390x:
commit 3213ed77
"Update math: redirect roundeven function"

(cherry picked from commit 259a17cc)