drop unused CString ctor case

`Value::CZString::CZString(char const* str, unsigned length, DuplicationPolicy allocate)` with `allocate == duplicate` does not happen.

Author: cdunn2001

src/lib_json/json_value.cpp

@@ -196,8 +196,9 @@ void Value::CommentInfo::setComment(const char* text, size_t len) {
 Value::CZString::CZString(ArrayIndex index) : cstr_(0), index_(index) {}
 
 Value::CZString::CZString(char const* str, unsigned length, DuplicationPolicy allocate)
-    : cstr_(allocate == duplicate ? duplicateStringValue(str, length) : str)
+    : cstr_(str)
 {
+  // allocate != duplicate
   storage_.policy_ = allocate;
   storage_.length_ = length;
 }