The "UBI" that the latest Keycloak images are based on has a glibc
compiled to only work on x86-64-v2 systems, and in some regions we
seem to sometimes get hypervisors reporting older processor
architectures where it won't work. Check CPU flags for sse4_2
support as an indicator, and abort launching if it's not present.
Change-Id: Ib0f482a939f94e801c82f3583e0a58dc4ca1f35c