Style: Replace header guards with #pragma once

tests/test_macros.h

@@ -28,8 +28,7 @@
 /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
 /**************************************************************************/
 
-#ifndef TEST_MACROS_H
-#define TEST_MACROS_H
+#pragma once
 
 #include "display_server_mock.h"
 
@@ -478,5 +477,3 @@ public:
 			CHECK(string_list[i] == m_slices[i]);                                                \
 		}                                                                                        \
 	} while (false)
-
-#endif // TEST_MACROS_H