Merge pull request #12637 from savuor:fix/instr_ipp_ocl

Fixes for instrumentation of IPP and OCL (#12637)

* fixed warning about re-declaring variable when both IPP and instrumentation are enabled

* fixed segfault when no funName provided

* compilation fixed when both OCL and instrumentation are enabled

modules/core/src/system.cpp

@@ -1836,7 +1836,7 @@ FLAGS getFlags()
 
 NodeData::NodeData(const char* funName, const char* fileName, int lineNum, void* retAddress, bool alwaysExpand, cv::instr::TYPE instrType, cv::instr::IMPL implType)
 {
-    m_funName       = funName;
+    m_funName       = funName ? cv::String(funName) : cv::String();  // std::string doesn't accept NULL
     m_instrType     = instrType;
     m_implType      = implType;
     m_fileName      = fileName;