AlarmManagerService: explain some timerfd_create() failures

When AlarmManagerService is broken, starting the framework fails in
weird and inconsistent ways.  So if we detect your kernel is missing the
required timerfd support, give up immediately and explain why.

Bug: 28357356

Test: manually break timerfd_create syscall, check adb logcat during boot
Change-Id: Iaa153fca38e9cd8e801f3e71c3e1ae2351907828
Signed-off-by: Greg Hackmann <ghackmann@google.com>