re-run ./autogen.sh --noconfigure

[Graham Percival]

We've have two changes to the configure script, so please:
1. completely remove your build directory
2. go to your lilypond git dir, and run:
  ./autogen.sh --noconfigure
3. then run:
  mkdir -p build/
  cd build
  ../configure

If you do not follow those instructions, and end up with build
problems, then I have no sympathy.  Our build system is not robust
enough to expect it to work if you fail to follow these
instructions.  Patches for the build system are of course welcome.

Cheers,
- Graham