refactor: use <cstdio> over stdio.h

We currently use both. Consolidate on the former.

src/bitcoin-tx.cpp

@@ -27,9 +27,9 @@
 #include <util/system.h>
 #include <util/translation.h>
 
+#include <cstdio>
 #include <functional>
 #include <memory>
-#include <stdio.h>
 
 static bool fCreateBlank;
 static std::map<std::string,UniValue> registers;

src/httpserver.cpp

@@ -21,10 +21,10 @@
 #include <util/threadnames.h>
 #include <util/translation.h>
 
+#include <cstdio>
 #include <deque>
 #include <memory>
 #include <optional>
-#include <stdio.h>
 #include <stdlib.h>
 #include <string>
 

src/ipc/interfaces.cpp

@@ -12,10 +12,10 @@
 #include <tinyformat.h>
 #include <util/system.h>
 
+#include <cstdio>
 #include <functional>
 #include <memory>
 #include <stdexcept>
-#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <string>

src/qt/utilitydialog.cpp

@@ -17,7 +17,7 @@
 #include <util/system.h>
 #include <util/strencodings.h>
 
-#include <stdio.h>
+#include <cstdio>
 
 #include <QCloseEvent>
 #include <QLabel>

src/streams.h

@@ -13,11 +13,11 @@
 
 #include <algorithm>
 #include <assert.h>
+#include <cstdio>
 #include <ios>
 #include <limits>
 #include <optional>
 #include <stdint.h>
-#include <stdio.h>
 #include <string.h>
 #include <string>
 #include <utility>