Header guard symbols should match their file name to make guard
collisions less likely.

Cleaned up with scripts/clean-header-guards.pl, followed by some
renaming of new guard symbols picked by the script to better ones.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Message-Id: <20190315145123.28030-6-armbru@redhat.com>
[Rebase to master: update include/hw/net/ne2000-isa.h]