Ruby-exiv2 EXIF handling library now usable

I’ve implemented extension to library exiv2 and created project on
rubyforge: ruby-exiv2 long time ago. But there was a problem, that gem
wasn’t installable. Extension compiled, but no bundle (dynamic library)

Now, I’ve found the problem. I was keeping all .c files in subfolder
lib, and included extension from this folder. When gem was being
installed, make && make install && make clean was performed in subfolder
lib. make install kept the compiled extension in lib folder and make
clean deleted it. So, no extension left.

I’ve moved all source files to subfolder ext and now make install moves
compiled extension out of the make clean hands. So, now you can use
ruby-exiv2 library.