Include required header and use from std namespace

This fixes #156 by not depending on indirect inclusion and additionally
uses iswprint from the namespace where C++ requires it to be defined,
instead of where a lot of implementations (also) define it.

Author: muggenhor

HISTORY.md

@@ -7,6 +7,7 @@ None yet
 ### Bugfixes
 
 * Allow running all GTest cases without filter separation ([#144](https://github.com/cucumber/cucumber-cpp/pull/144) Giel van Schijndel)
+* Fix QNX build by depending on standard C++ instead of specific implementation ([#156](https://github.com/cucumber/cucumber-cpp/issues/156) Giel van Schijndel)
 
 ## [0.4](https://github.com/cucumber/cucumber-cpp/compare/v0.3.1...v0.4) (31 March 2017)
 

include/json_spirit/json_spirit_writer_template.h

@@ -9,6 +9,7 @@
 #include "json_spirit_value.h"
 
 #include <cassert>
+#include <cwctype>
 #include <sstream>
 #include <iomanip>
 
@@ -77,7 +78,7 @@ namespace json_spirit
 
             const wint_t unsigned_c( ( c >= 0 ) ? c : 256 + c );
 
-            if( iswprint( unsigned_c ) )
+            if( std::iswprint( unsigned_c ) )
             {
                 result += c;
             }