refactor: Move system from util to common library

Since the kernel library no longer depends on the system file, move it
to the common library instead in accordance to the diagram in
doc/design/libraries.md.

src/qt/bitcoin.cpp

@@ -11,6 +11,7 @@
 #include <chainparams.h>
 #include <common/args.h>
 #include <common/init.h>
+#include <common/system.h>
 #include <init.h>
 #include <interfaces/handler.h>
 #include <interfaces/init.h>
@@ -32,7 +33,6 @@
 #include <uint256.h>
 #include <util/exception.h>
 #include <util/string.h>
-#include <util/system.h>
 #include <util/threadnames.h>
 #include <util/translation.h>
 #include <validation.h>

src/qt/bitcoingui.cpp

@@ -30,16 +30,17 @@
 #include <qt/macdockiconhandler.h>
 #endif
 
-#include <functional>
 #include <chain.h>
 #include <chainparams.h>
+#include <common/system.h>
 #include <interfaces/handler.h>
 #include <interfaces/node.h>
 #include <node/interface_ui.h>
-#include <util/system.h>
 #include <util/translation.h>
 #include <validation.h>
 
+#include <functional>
+
 #include <QAction>
 #include <QActionGroup>
 #include <QApplication>

src/qt/clientmodel.cpp

@@ -12,11 +12,11 @@
 
 #include <clientversion.h>
 #include <common/args.h>
+#include <common/system.h>
 #include <interfaces/handler.h>
 #include <interfaces/node.h>
 #include <net.h>
 #include <netbase.h>
-#include <util/system.h>
 #include <util/threadnames.h>
 #include <util/time.h>
 #include <validation.h>

src/qt/optionsdialog.cpp

@@ -15,11 +15,11 @@
 #include <qt/guiutil.h>
 #include <qt/optionsmodel.h>
 
+#include <common/system.h>
 #include <interfaces/node.h>
-#include <validation.h> // for DEFAULT_SCRIPTCHECK_THREADS and MAX_SCRIPTCHECK_THREADS
 #include <netbase.h>
-#include <txdb.h> // for -dbcache defaults
-#include <util/system.h>
+#include <txdb.h>
+#include <validation.h>
 
 #include <chrono>
 

src/qt/rpcconsole.cpp

@@ -10,6 +10,7 @@
 #include <qt/forms/ui_debugwindow.h>
 
 #include <chainparams.h>
+#include <common/system.h>
 #include <interfaces/node.h>
 #include <qt/bantablemodel.h>
 #include <qt/clientmodel.h>
@@ -21,7 +22,6 @@
 #include <rpc/server.h>
 #include <util/strencodings.h>
 #include <util/string.h>
-#include <util/system.h>
 #include <util/threadnames.h>
 
 #include <univalue.h>

src/qt/splashscreen.cpp

@@ -9,13 +9,13 @@
 #include <qt/splashscreen.h>
 
 #include <clientversion.h>
+#include <common/system.h>
 #include <interfaces/handler.h>
 #include <interfaces/node.h>
 #include <interfaces/wallet.h>
 #include <qt/guiutil.h>
 #include <qt/networkstyle.h>
 #include <qt/walletmodel.h>
-#include <util/system.h>
 #include <util/translation.h>
 
 #include <functional>

src/qt/test/rpcnestedtests.cpp

@@ -4,12 +4,12 @@
 
 #include <qt/test/rpcnestedtests.h>
 
+#include <common/system.h>
 #include <interfaces/node.h>
-#include <rpc/server.h>
 #include <qt/rpcconsole.h>
+#include <rpc/server.h>
 #include <test/util/setup_common.h>
 #include <univalue.h>
-#include <util/system.h>
 
 #include <QTest>
 

src/qt/transactiondesc.cpp

@@ -13,12 +13,12 @@
 #include <qt/paymentserver.h>
 #include <qt/transactionrecord.h>
 
+#include <common/system.h>
 #include <consensus/consensus.h>
 #include <interfaces/node.h>
 #include <interfaces/wallet.h>
 #include <key_io.h>
 #include <policy/policy.h>
-#include <util/system.h>
 #include <validation.h>
 #include <wallet/types.h>