Here comes a slightly updated spkg:
http://perso.telecom-paristech.fr/~flori/sage/valgrind-3.7.0.p0.spkg
I've applied the two mentioned patches and rerun autogen.sh to regenerate the build system files.
The package installs and seems functional with my Sage installation.
Another solution whould be to properly package a recent valgrind svn version, although I'd prefer to use this light solution and wait for a proper stable release to make a real update to valgrind.
Feel free to disagree and rant here.