Utils: Drop unused headers [A-H]

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

Change-Id: I838a8324ddd5b4d8d5a51b8f30605f783c663813
Reviewed-by: hjk <hjk@qt.io>

src/libs/utils/environmentdialog.cpp

@@ -25,13 +25,7 @@
 
 #include "environmentdialog.h"
 
-#include <utils/environment.h>
-#include <utils/hostosinfo.h>
-
-#include <QVBoxLayout>
-#include <QDialogButtonBox>
-#include <QPlainTextEdit>
-#include <QLabel>
+#include "environment.h"
 
 namespace Utils {