Do not require ctype/stdio if not needed

libdevcore/CommonIO.cpp

@@ -23,7 +23,6 @@
 #include <iostream>
 #include <cstdlib>
 #include <fstream>
-#include <stdio.h>
 #if defined(_WIN32)
 #include <windows.h>
 #else

libsolidity/inlineasm/AsmParser.cpp

@@ -26,7 +26,7 @@
 
 #include <boost/algorithm/string.hpp>
 
-#include <ctype.h>
+#include <cctype>
 #include <algorithm>
 
 using namespace std;

libsolidity/parsing/Parser.cpp

@@ -20,7 +20,7 @@
  * Solidity parser.
  */
 
-#include <ctype.h>
+#include <cctype>
 #include <vector>
 #include <libevmasm/SourceLocation.h>
 #include <libsolidity/parsing/Parser.h>

test/libsolidity/ASTJSONTest.cpp

@@ -22,7 +22,6 @@
 #include <boost/algorithm/string.hpp>
 #include <boost/algorithm/string/predicate.hpp>
 #include <boost/throw_exception.hpp>
-#include <cctype>
 #include <fstream>
 #include <memory>
 #include <stdexcept>

test/libsolidity/SyntaxTest.cpp

@@ -20,7 +20,6 @@
 #include <boost/algorithm/string.hpp>
 #include <boost/algorithm/string/predicate.hpp>
 #include <boost/throw_exception.hpp>
-#include <cctype>
 #include <fstream>
 #include <memory>
 #include <stdexcept>