Merge remote-tracking branch 'remotes/armbru/tags/pull-misc-2019-05-13' into staging

Miscellaneous patches for 2019-05-13

# gpg: Signature made Mon 13 May 2019 08:04:02 BST
# gpg:                using RSA key 3870B400EB918653
# gpg: Good signature from "Markus Armbruster <armbru@redhat.com>" [full]
# gpg:                 aka "Markus Armbruster <armbru@pond.sub.org>" [full]
# Primary key fingerprint: 354B C8B3 D7EB 2A6B 6867  4E5F 3870 B400 EB91 8653

* remotes/armbru/tags/pull-misc-2019-05-13:
  Clean up decorations and whitespace around header guards
  Normalize header guard symbol definition.
  Clean up ill-advised or unusual header guards
  Clean up header guards that don't match their file name
  target/xtensa: Clean up core-isa.h header guards
  linux-user/nios2 linux-user/riscv: Clean up header guards
  authz: Normalize #include "authz/trace.h" to "trace.h"
  Use #include "..." for our own headers, <...> for others
  Clean up includes

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>