fix xf86-video-intel

without --enable-xvmc, the file i810_hwmc.c, containing I810InitMC(),
doesn't get compiled, but is referenced from elsewhere.
probably the reference is in some dead code path, so this bug went
unnoticed with glibc's dynlinker, which supports lazy loading,
unlike musl's.
python-slowaes: fix deps
add electrum, a lightweight bitcoin client
python-ecdsa: bump to 0.10