Style: Replace header guards with #pragma once

core/crypto/hashing_context.h

@@ -28,8 +28,7 @@
 /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
 /**************************************************************************/
 
-#ifndef HASHING_CONTEXT_H
-#define HASHING_CONTEXT_H
+#pragma once
 
 #include "core/object/ref_counted.h"
 
@@ -62,5 +61,3 @@ public:
 };
 
 VARIANT_ENUM_CAST(HashingContext::HashType);
-
-#endif // HASHING_CONTEXT_H