Fix memory leak when building with a11y support

QAccessible::updateAccessibility() expects a pointer, but doesn't take
ownership of the argument and expects us to delete it after we've called
it. So just allocate the object on the stack like other users of this
API do.

Found by ASAN.

src/TerminalDisplay.cpp

@@ -1259,8 +1259,10 @@ void TerminalDisplay::updateImage()
     delete[] dirtyMask;
 
 #ifndef QT_NO_ACCESSIBILITY
-    QAccessible::updateAccessibility(new QAccessibleEvent(this, QAccessible::VisibleDataChanged));
-    QAccessible::updateAccessibility(new QAccessibleTextCursorEvent(this, _usedColumns * screenWindow()->screen()->getCursorY() + screenWindow()->screen()->getCursorX()));
+    QAccessibleEvent dataChangeEvent(this, QAccessible::VisibleDataChanged);
+    QAccessible::updateAccessibility(&dataChangeEvent);
+    QAccessibleTextCursorEvent cursorEvent(this, _usedColumns * screenWindow()->screen()->getCursorY() + screenWindow()->screen()->getCursorX());
+    QAccessible::updateAccessibility(&cursorEvent);
 #endif
 }
 
@@ -3143,7 +3145,8 @@ void TerminalDisplay::keyPressEvent(QKeyEvent* event)
     emit keyPressedSignal(event);
 
 #ifndef QT_NO_ACCESSIBILITY
-    QAccessible::updateAccessibility(new QAccessibleTextCursorEvent(this, _usedColumns * screenWindow()->screen()->getCursorY() + screenWindow()->screen()->getCursorX()));
+    QAccessibleTextCursorEvent textCursorEvent(this, _usedColumns * screenWindow()->screen()->getCursorY() + screenWindow()->screen()->getCursorX());
+    QAccessible::updateAccessibility(&textCursorEvent);
 #endif
 
     event->accept();