Clean up ill-advised or unusual header guards

Leading underscores are ill-advised because such identifiers are
reserved.  Trailing underscores are merely ugly.  Strip both.

Our header guards commonly end in _H.  Normalize the exceptions.

Macros should be ALL_CAPS.  Normalize the exception.

Done with scripts/clean-header-guards.pl.

include/hw/xen/interface/ and tools/virtiofsd/ left alone, because
these were imported from Xen and libfuse respectively.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20220506134911.2856099-3-armbru@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

bsd-user/arm/target_arch_cpu.h

@@ -17,8 +17,8 @@
  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef _TARGET_ARCH_CPU_H_
-#define _TARGET_ARCH_CPU_H_
+#ifndef TARGET_ARCH_CPU_H
+#define TARGET_ARCH_CPU_H
 
 #include "target_arch.h"
 #include "signal-common.h"
@@ -210,4 +210,4 @@ static inline void target_cpu_reset(CPUArchState *env)
 {
 }
 
-#endif /* !_TARGET_ARCH_CPU_H */
+#endif /* TARGET_ARCH_CPU_H */