If opencv failed for this Alex images it means that it's uclibc image?
Yes, all my ones are uClibc-based, I've added a note to README files about that.
You can check the image's libc implementation by running the below command and looking for the output listed.
root@quark:~# opkg list-installed|grep uclibc
uclibc - 0.9.33+git0+946799cd0ce0c6c803c9cb173a84f4d607bde350-r8.4
uclibc-dbg - 0.9.33+git0+946799cd0ce0c6c803c9cb173a84f4d607bde350-r8.4
uclibc-dev - 0.9.33+git0+946799cd0ce0c6c803c9cb173a84f4d607bde350-r8.4
Right now, AFAIK, Python bindings indeed don't work on the uClibc image, just like already mentioned by mhahn. One can still use C++, it works fine.