ocl: refactor Program API

- don't store ProgramSource in compiled Programs (resolved problem with "source" buffers lifetime)
- completelly remove Program::read/write methods implementation:
  - replaced with method to query RAW OpenCL binary without any "custom" data
- deprecate Program::getPrefix() methods

modules/core/include/opencv2/core/ocl.hpp

@@ -606,19 +606,14 @@ public:
 
     bool create(const ProgramSource& src,
                 const String& buildflags, String& errmsg);
-    bool read(const String& buf, const String& buildflags); // deprecated
-    bool write(String& buf) const; // deprecated
 
-    const ProgramSource& source() const; // deprecated
     void* ptr() const;
 
-    String getPrefix() const; // deprecated
-    static String getPrefix(const String& buildflags); // deprecated
-
-
     /**
      * @brief Query device-specific program binary.
      *
+     * Returns RAW OpenCL executable binary without additional attachments.
+     *
      * @sa ProgramSource::fromBinary
      *
      * @param[out] binary output buffer
@@ -629,6 +624,15 @@ public:
     inline Impl* getImpl() const { return (Impl*)p; }
 protected:
     Impl* p;
+public:
+#ifndef OPENCV_REMOVE_DEPRECATED_API
+    // TODO Remove this
+    CV_DEPRECATED bool read(const String& buf, const String& buildflags); // removed, use ProgramSource instead
+    CV_DEPRECATED bool write(String& buf) const; // removed, use getBinary() method instead (RAW OpenCL binary)
+    CV_DEPRECATED const ProgramSource& source() const; // implementation removed
+    CV_DEPRECATED String getPrefix() const; // deprecated, implementation replaced
+    CV_DEPRECATED static String getPrefix(const String& buildflags); // deprecated, implementation replaced
+#endif
 };