s390x: Check HWCAP bits against compiler flags

When compiled with GCC 11.1 and -march=z14 -O3 build flags, running
ld.so (or any dynamically linked program) prints:

Fatal glibc error: CPU lacks VXE support (z14 or later required)

Co-Authored-By: Stefan Liebler <stli@linux.ibm.com>
Reviewed-by: Stefan Liebler <stli@linux.ibm.com>