This patch adds an ifunc variant to use the cu instruction on arch12 CPUs.
This new ifunc variant can be built if binutils support z13 vector
instructions. At runtime, HWCAP_S390_VXE decides if we can use the
cu21 instruction.
ChangeLog:
* sysdeps/s390/utf8-utf16-z9.c (__to_utf8_loop_vx_cu):
Use vector and cu21 instruction.
* sysdeps/s390/multiarch/utf8-utf16-z9.c:
Add __to_utf8_loop_vx_cu in ifunc resolver.
