FWIW, after installing Ubuntu 13.10 and seeing my ../configure choke on the
mpost version, I followede Werner Lemberg's suggestion from here:
http://article.gmane.org/gmane.comp.gnu.lilypond.devel/55828/match=mpost+broken
and all seems to be well. At least, I was able to make and install lilypond,
then make and install the docs with no apparent errors, and that resulted in no
obviously broken glyphs or flags in a quick test compile. Since the fix
involves a quick download and replace, I'm wondering if it's *too* easy, but so
far so good!