message: core(ocl): update isOpenCLActivated()
  reuse g_isOpenCLAvailable variable instead
diff: @@ -830,13 +830,12 @@ public:
  // true if we have initialized OpenCL subsystem with available platforms
  -static bool g_isOpenCVActivated = false;
  +static bool g_isOpenCLInitialized = false;
  +static bool g_isOpenCLAvailable = false;
  bool haveOpenCL()
  {
  CV_TRACE_FUNCTION();
  - static bool g_isOpenCLInitialized = false;
  - static bool g_isOpenCLAvailable = false;
  if (!g_isOpenCLInitialized)
  {
  @@ -855,7 +854,7 @@ bool haveOpenCL()
  {
  cl_uint n = 0;
  g_isOpenCLAvailable = ::clGetPlatformIDs(0, NULL, &n) == CL_SUCCESS;
  - g_isOpenCVActivated = n > 0;
  + g_isOpenCLAvailable &= n > 0;
  }
  catch (...)
  {
  @@ -885,7 +884,7 @@ bool useOpenCL()
  bool isOpenCLActivated()
  {
  - if (!g_isOpenCVActivated)
  + if (!g_isOpenCLAvailable)
  return false; // prevent unnecessary OpenCL activation via useOpenCL()->haveOpenCL() calls
  return useOpenCL();
  }
  @@ -5773,7 +5772,6 @@ public:
  static OpenCLAllocator* getOpenCLAllocator_() // call once guarantee
  {
  static OpenCLAllocator* g_allocator = new OpenCLAllocator(); // avoid destructor call (using of this object is too wide)
  - g_isOpenCVActivated = true;
  return g_allocator;
  }
  MatAllocator* getOpenCLAllocator()
  