bmpx is broken in rawhide because of the libsoup upgrade. Here are some patches, which compile but are otherwise untested. Alternatively, you might want to wait for bug 430756 (compat-libsoup). I haven't filed this upstream because I didn't feel like creating an account on their bugtracker (and because as I said, the patches are completely untested).
Created attachment 293476 [details] patch to build bmpx with libsoup-2.4
Thank you Dan. The patch works well (after changing some stuff and adding a regenerated configure script) but bmpx is broken too heavily due to changes in gcc-4.3, i.e. too many files are missing an explicit cstring include so I'll wait till upstream fixes it and remove bmpx from rawhide for now.