How does this interact with CPU_COUNT, which is documented in the
Contributor's Guide thus (emphasis mine)?
The most time consuming task for building the documentation is
running LilyPond to build images of music, and *** there cannot be
several simultaneously running lilypond-book instances, *** so the
-j make option does not significantly speed up the build
process. To help speed it up, the makefile variable CPU_COUNT may
be set in local.make or on the command line to the number of .ly
files that LilyPond should process simultaneously, e.g. on a
bi-processor or dual core machine:
make -j3 CPU_COUNT=3 doc
This is how I always build. Is it going to have the same effect now, or
will it do something new, e.g. attempt 9 concurrent jobs?
https://codereview.appspot.com/569400043/
