message: make -fvisibility=hidden work with java 1.7
diff: @@ -16,6 +16,17 @@ extern "C" {
  #endif
  #include <jni.h>
  +// make -fvisibility=hidden work with java 1.7
  +#if defined(__linux__) && !defined(__ANDROID__) && !defined (JNI_VERSION_1_8)
  + // adapted from jdk1.8/jni.h
  + #if (defined(__GNUC__) && ((__GNUC__ > 4) || (__GNUC__ == 4) && (__GNUC_MINOR__ > 2))) || __has_attribute(visibility)
  + #undef JNIEXPORT
  + #define JNIEXPORT __attribute__((visibility("default")))
  + #undef JNIIMPORT
  + #define JNIIMPORT __attribute__((visibility("default")))
  + #endif
  +#endif
  +
  } // extern "C"
  #include "opencv_java.hpp"
  