jsoncpp: Drop doxygen comments not recognized by Clang

Some Clang versions warn with `-Wdocumentation-unknown-command` about
the `\internal` and `\snippet` command tag names.

Utilities/cmjsoncpp/include/json/reader.h

@@ -356,13 +356,13 @@ public:
   /** Called by ctor, but you can use this to reset settings_.
    * \pre 'settings' != NULL (but Json::null is fine)
    * \remark Defaults:
-   * \snippet src/lib_json/json_reader.cpp CharReaderBuilderDefaults
+   * snippet src/lib_json/json_reader.cpp CharReaderBuilderDefaults
    */
   static void setDefaults(Json::Value* settings);
   /** Same as old Features::strictMode().
    * \pre 'settings' != NULL (but Json::null is fine)
    * \remark Defaults:
-   * \snippet src/lib_json/json_reader.cpp CharReaderBuilderStrictMode
+   * snippet src/lib_json/json_reader.cpp CharReaderBuilderStrictMode
    */
   static void strictMode(Json::Value* settings);
 };

Utilities/cmjsoncpp/include/json/value.h

@@ -787,7 +787,7 @@ public:
   ValueConstIterator(ValueIterator const& other);
 
 private:
-/*! \internal Use by Value to create an iterator.
+/*! internal Use by Value to create an iterator.
  */
   explicit ValueConstIterator(const Value::ObjectValues::iterator& current);
 public:
@@ -838,7 +838,7 @@ public:
   ValueIterator(const ValueIterator& other);
 
 private:
-/*! \internal Use by Value to create an iterator.
+/*! internal Use by Value to create an iterator.
  */
   explicit ValueIterator(const Value::ObjectValues::iterator& current);
 public:

Utilities/cmjsoncpp/include/json/writer.h

@@ -135,7 +135,7 @@ public:
   /** Called by ctor, but you can use this to reset settings_.
    * \pre 'settings' != NULL (but Json::null is fine)
    * \remark Defaults:
-   * \snippet src/lib_json/json_writer.cpp StreamWriterBuilderDefaults
+   * snippet src/lib_json/json_writer.cpp StreamWriterBuilderDefaults
    */
   static void setDefaults(Json::Value* settings);
 };

Utilities/cmjsoncpp/src/lib_json/json_value.cpp

@@ -348,7 +348,7 @@ bool Value::CZString::isStaticString() const { return storage_.policy_ == noDupl
 // //////////////////////////////////////////////////////////////////
 // //////////////////////////////////////////////////////////////////
 
-/*! \internal Default constructor initialization must be equivalent to:
+/*! internal Default constructor initialization must be equivalent to:
  * memset( this, 0, sizeof(Value) )
  * This optimization is used in ValueInternalMap fast allocator.
  */