Utils: Drop unused headers [I-Z]

Round 2 - focus on sources.
For classes with initial in range [I-Z].
Try to keep the same separators between different kind of headers.

Change-Id: I8a7ab99bab8120ee72cda6433ee3dc6f260a4d76
Reviewed-by: hjk <hjk@qt.io>

src/libs/utils/stylehelper.cpp

@@ -27,8 +27,7 @@
 
 #include "theme/theme.h"
 #include "hostosinfo.h"
-
-#include <utils/qtcassert.h>
+#include "qtcassert.h"
 
 #include <QApplication>
 #include <QCommonStyle>