uml: host TLS diagnostics

Add some diagnostics when TLS operations on the host fail.  Also spit out more
information about the TLS environment on the host at boot time.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>