I was having the same problem, usung Ubuntu Breezy. No idea why it wouldn't compile, unless there's a gcc version compatibility issue. i used a really crude work-around (I just commented the offending structure out of the code), but it seems to have worked and, with some minor complaints from gcc during the make, i'm playing wma files without any problems. here's what i did, step by step:
in a terminal, from the bmp-wma-0.1.1 directory, type "cd src/libffwma"
open the file "common.h", which is causing all the problems, using your favorite text editor. i use emacs, but it's not a standard intall option with ubuntu breezy; vim is, which i don't know. so, use what you want, but the point is, scroll down to line 67, which should be blank. line 68 should define the struct AVOption. On line 67, type "/*", then on line 75 type "*/". save the file, close it, and then run "make" again. it should give some warnings, but no errors. next, run "sudo make install", which will run with no problems. And then you should be able to play wma files in bmp.
i don't know the code well enough to really know what this does, so I don't recommend doing it unless you're definitely getting the same error message as in the original post on this thread, because you might end up making things worse. that said, the worst that could happen is that you would crash BMP (it didn't do it on my computer), and you can always just uninstall bmp and reinstall it without being any worse for the wear.