Fix many mistakes & inconsistencies in header file layout

This introduces a syntax-check script that validates header files use a
common layout:

  /*
   ...copyright header...
   */
  <one blank line>
  #ifndef SYMBOL
  # define SYMBOL
  ....content....
  #endif /* SYMBOL */

For any file ending priv.h, before the #ifndef, we will require a
guard to prevent bogus imports:

  #ifndef SYMBOL_ALLOW
  # error ....
  #endif /* SYMBOL_ALLOW */
  <one blank line>

The many mistakes this script identifies are then fixed.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

tests/testutilsqemuschema.h

@@ -16,9 +16,12 @@
  * <http://www.gnu.org/licenses/>.
  */
 
-#include "virhash.h"
-#include "virjson.h"
-#include "virbuffer.h"
+#ifndef __TESTUTILSQEMUSCHEMA_H__
+# define __TESTUTILSQEMUSCHEMA_H__
+
+# include "virhash.h"
+# include "virjson.h"
+# include "virbuffer.h"
 
 int
 testQEMUSchemaValidate(virJSONValuePtr obj,
@@ -31,3 +34,5 @@ testQEMUSchemaGetLatest(void);
 
 virHashTablePtr
 testQEMUSchemaLoad(void);
+
+#endif /* __TESTUTILSQEMUSCHEMA_H__ */