Extract MakeUnique into utilmemory.h

And use it to reduce chainparamsbase's direct reliance on util.h to
only args handling.

utilmemory.h can be replaced with <memory> once we move to C++14.

src/Makefile.am

@@ -179,6 +179,7 @@ BITCOIN_CORE_H = \
   ui_interface.h \
   undo.h \
   util.h \
+  utilmemory.h \
   utilmoneystr.h \
   utiltime.h \
   validation.h \

src/chainparamsbase.cpp

@@ -7,6 +7,7 @@
 
 #include <tinyformat.h>
 #include <util.h>
+#include <utilmemory.h>
 
 #include <assert.h>
 

src/interfaces/handler.cpp

@@ -4,7 +4,7 @@
 
 #include <interfaces/handler.h>
 
-#include <util.h>
+#include <utilmemory.h>
 
 #include <boost/signals2/connection.hpp>
 #include <utility>

src/util.h

@@ -1,5 +1,5 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
-// Copyright (c) 2009-2017 The Bitcoin Core developers
+// Copyright (c) 2009-2018 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -20,11 +20,11 @@
 #include <sync.h>
 #include <tinyformat.h>
 #include <utiltime.h>
+#include <utilmemory.h>
 
 #include <atomic>
 #include <exception>
 #include <map>
-#include <memory>
 #include <set>
 #include <stdint.h>
 #include <string>
@@ -346,13 +346,6 @@ template <typename Callable> void TraceThread(const char* name,  Callable func)
 
 std::string CopyrightHolders(const std::string& strPrefix);
 
-//! Substitute for C++14 std::make_unique.
-template <typename T, typename... Args>
-std::unique_ptr<T> MakeUnique(Args&&... args)
-{
-    return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
-}
-
 /**
  * On platforms that support it, tell the kernel the calling thread is
  * CPU-intensive and non-interactive. See SCHED_BATCH in sched(7) for details.

src/utilmemory.h

@@ -0,0 +1,19 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2018 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_UTILMEMORY_H
+#define BITCOIN_UTILMEMORY_H
+
+#include <memory>
+#include <utility>
+
+//! Substitute for C++14 std::make_unique.
+template <typename T, typename... Args>
+std::unique_ptr<T> MakeUnique(Args&&... args)
+{
+    return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
+}
+
+#endif