core: eliminate redundant cv::format() declarations

Existed includes sequence:
- utility.hpp -> core.hpp -> operations.hpp

modules/core/include/opencv2/core/operations.hpp

@@ -365,6 +365,12 @@ template<typename _Tp> static inline _Tp randu()
 
 ///////////////////////////////// Formatted string generation /////////////////////////////////
 
+/** @brief Returns a text string formatted using the printf-like expression.
+
+The function acts like sprintf but forms and returns an STL string. It can be used to form an error
+message in the Exception constructor.
+@param fmt printf-compatible formatting specifiers.
+ */
 CV_EXPORTS String format( const char* fmt, ... );
 
 ///////////////////////////////// Formatted output of cv::Mat /////////////////////////////////

modules/core/include/opencv2/core/utility.hpp

@@ -182,13 +182,6 @@ extern "C" typedef int (*ErrorCallback)( int status, const char* func_name,
 */
 CV_EXPORTS ErrorCallback redirectError( ErrorCallback errCallback, void* userdata=0, void** prevUserdata=0);
 
-/** @brief Returns a text string formatted using the printf-like expression.
-
-The function acts like sprintf but forms and returns an STL string. It can be used to form an error
-message in the Exception constructor.
-@param fmt printf-compatible formatting specifiers.
- */
-CV_EXPORTS String format( const char* fmt, ... );
 CV_EXPORTS String tempfile( const char* suffix = 0);
 CV_EXPORTS void glob(String pattern, std::vector<String>& result, bool recursive = false);