Fix issue open-source-parsers#567 in writing real values in different locales

The output of snprintf might produce ',' separators for decimal places if
certain locales are set. This commit moves the converversion from ',' to '.'
to correct place. Otherwise an additional ".0" might be appended.

Author: bernhardHartleb

src/lib_json/json_writer.cpp

@@ -150,7 +150,8 @@ JSONCPP_STRING valueToString(double value, bool useSpecialFloats, unsigned int p
   // concepts of reals and integers.
   if (isfinite(value)) {
     len = snprintf(buffer, sizeof(buffer), formatString, value);
-    
+    fixNumericLocale(buffer, buffer + len);
+
     // try to ensure we preserve the fact that this was given to us as a double on input
     if (!strstr(buffer, ".") && !strstr(buffer, "e")) {
       strcat(buffer, ".0");
@@ -165,10 +166,8 @@ JSONCPP_STRING valueToString(double value, bool useSpecialFloats, unsigned int p
     } else {
       len = snprintf(buffer, sizeof(buffer), useSpecialFloats ? "Infinity" : "1e+9999");
     }
-    // For those, we do not need to call fixNumLoc, but it is fast.
   }
   assert(len >= 0);
-  fixNumericLocale(buffer, buffer + len);
   return buffer;
 }
 }