Utils: Modernize further

Many issues, mostly in headers, were not addressed in
e38410b76c

modernize-use-auto
modernize-use-nullptr
modernize-use-override
modernize-use-using
modernize-use-default-member-init
modernize-use-equals-default

Change-Id: I320a51726db881e582b898948d53735ebb06887a
Reviewed-by: hjk <hjk@qt.io>

src/libs/utils/overridecursor.cpp

@@ -30,7 +30,7 @@
 using namespace Utils;
 
 OverrideCursor::OverrideCursor(const QCursor &cursor)
-    : m_set(true), m_cursor(cursor)
+    : m_cursor(cursor)
 {
     QApplication::setOverrideCursor(cursor);
 }