Fix header file include guard names

Make the include guards consistent by renaming them systematically according
to the naming conventions below

For the public header files (in the 'include/openssl' directory), the guard
names try to match the path specified in the include directives, with
all letters converted to upper case and '/' and '.' replaced by '_'. For the
private header files files, an extra 'OSSL_' is added as prefix.

Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/9333)
diff --git a/test/testutil.h b/test/testutil.h
index f7d00dc..57ab153 100644
--- a/test/testutil.h
+++ b/test/testutil.h
@@ -7,8 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#ifndef HEADER_TESTUTIL_H
-# define HEADER_TESTUTIL_H
+#ifndef OSSL_TESTUTIL_H
+# define OSSL_TESTUTIL_H
 
 #include <stdarg.h>
 
@@ -548,4 +548,4 @@
 /* Create a file path from a directory and a filename */
 char *test_mk_file_path(const char *dir, const char *file);
 
-#endif                          /* HEADER_TESTUTIL_H */
+#endif                          /* OSSL_TESTUTIL_H */